French soldiers patrol at Charles de Gaulle airport, outside of Paris, Friday, May 20, 2016. The search continued on Friday for missing EgyptAir flight 804, which disappeared from the radar while carrying... (Associated Press) 
 
 CAIRO (AP) — Smoke was detected in multiple places on EgyptAir flight 804 moments before it plummeted into the Mediterranean, but the cause of the crash that killed all 66 on board remains unclear, the French air accident investigation agency said on Saturday. 
 
 Agency spokesman Sebastien Barthe told The Associated Press in Paris that the plane's automatic detection system sent messages indicating smoke a few minutes before the plane disappeared from radar while flying over the east Mediterranean early on Thursday morning. 
 
 The messages, he explained, "generally mean the start of a fire," but he added: "We are drawing no conclusions from this. Everything else is pure conjecture." 
 
 Looking for clues to whether terrorists may have brought down the Airbus A320, investigators have been poring over the passenger list and questioned ground crew members at Charles de Gaulle Airport in Paris, from which the plane took off. 
 
 The aircraft had been cruising normally in clear skies on a nighttime flight to Cairo early Thursday when it suddenly lurched left, then right, spun all the way around and plummeted 38,000 feet (11,582.4 meters) into the sea, never issuing a distress signal. 
 
 Search crews are scouring for further wreckage of the aircraft. Experts said answers will come only with an examination of the wreckage and the plane's cockpit voice and flight data recorders, commonly known as black boxes. 
 
 Planes and vessels from Egypt and five other countries — Greece, Britain, France, the United States and Cyprus — continued searching a wide area of the eastern Mediterranean on Saturday, a day after the Egyptian military found debris from the passenger jet in the sea 180 miles (290 kilometers) north of the Egyptian port city of Alexandria. 
 
 The waters in the area are 8,000 to 10,000 feet deep (2,440 to 3,050 meters), and the pings from the black boxes can be detected up to a depth of 20,000 feet (6 kilometers). 
 
 On Saturday, the Egyptian military released photographs of the debris from EgyptAir flight 804. The photos were posted on the Facebook page of the chief military spokesman. They appear to show the heavily-damaged remains of plane seats, life jackets — one of which was seemingly undamaged — and a scrap of cloth that looks to be part of a baby's purple and pink blanket or sleeping bag. 
 
 The spokesman's Facebook page later posted a brief video that showed more debris, including what appeared to be a piece of blue carpet, seat belts, a shoe and what looked like a woman's white handbag. The short clip opened with aerial footage of an unidentified navy ship followed by a speed boat with five service members aboard heading toward floating debris. 
 
 Egyptian authorities said they believe terrorism is a more likely explanation than equipment failure, and some aviation experts have said the erratic flight suggests a bomb blast or a struggle in the cockpit. But so far no hard evidence has emerged. 
 
 No militant group has claimed to have brought down the aircraft. That is a contrast to the downing of a Russian jet in October over Egypt's Sinai Peninsula that killed all 224 on board. In that case, the Islamic State group's branch in Sinai issued a claim of responsibility within hours. On Friday, IS issued a statement on clashes with the Egyptian military in Sinai, but said nothing about the plane crash. 
 
 Three European security officials said on Friday that the passenger manifest for Flight 804 contained no names on terrorism watch lists. The officials spoke on condition of anonymity because they were not authorized to discuss the investigation. The manifest was leaked online and has not been verified by the airline. 
 
 Further checks are being conducted on relatives of the passengers. 
 
 French aviation investigators have begun to check and question all baggage handlers, maintenance workers, gate agents and other ground crew members at Charles de Gaulle Airport who had a direct or indirect link to the plane before it took off, according to a French judicial official. The official was not authorized to discuss the investigation and spoke on condition of anonymity. 
 
 Whatever caused the aircraft to crash, the tragedy will most likely deepen Egypt's difficult predicament as it struggles to revive a battered economy and contain an increasingly resilient insurgency by Islamic militants. 
 
 In the five years since the country was first mired in turmoil caused by a popular uprising against longtime autocrat Hosni Mubarak, the lucrative tourism sector has been decimated, the value of the local currency has progressively fallen and domestic debt has mushroomed. 
 
 While the latest tragedy may not reflect directly on security at Egypt's airports, as the Russian jet crash did in October, the country's association with another air disaster will impact negatively on tourism and the flow of foreign investment. 
 
 In Paris, French Foreign Minister Jean-Marc Ayrault said Saturday that he and other officials — including representatives of Paris Aeroport, the French prosecutor, EgyptAir, and the Egyptian ambassador to Paris — had met with about 100 family members to express "our profound compassion" over the crash. 
 
 In a statement delivered to reporters following the meeting, he said: "All the hypotheses are being examined — none are being favored." 
 
 "In the name of France, once more, I am expressing my solidarity, but also our affection ... for all those people who learned that a loved one, or even an entire family, have drowned in the sea — and who want to know, to know to be able to grieve. It's a difficult moment, a painful moment. I wanted to say it again: We're on their side." 
 
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 Satter reported from Paris. Associated Press writers Angela Charlton and Philippe Sotto in Paris and Paisley Dodds in London contributed to this report. ||||| This still image taken from video posted Saturday, May 21, 2016, on the official Facebook page of the Egyptian Armed Forces spokesman shows a piece of carpet from the wreckage of EgyptAir flight 804.... (Associated Press) 
 
 This still image taken from video posted Saturday, May 21, 2016, on the official Facebook page of the Egyptian Armed Forces spokesman shows a piece of carpet from the wreckage of EgyptAir flight 804. Smoke was detected in multiple places on EgyptAir flight 804 moments before it plummeted into the Mediterranean,... (Associated Press) 
 
 CAIRO (AP) — Egypt's president said on Sunday a submarine belonging to his country's Oil Ministry was headed to the site of the crash of EgyptAir Flight-804 in the eastern Mediterranean to join the search for the cockpit voice and flight data recorders, commonly known as black boxes. 
 
 President Abdel-Fattah el-Sissi also said Egypt was jointly investigating the Thursday crash with the French government. "It is very, very important to us to establish the circumstances that led to the crash of that aircraft," he said in comments broadcast live on Egyptian TV channels. 
 
 He said the submarine, which has the capacity to operate at a depth of 3,000 meters (9842 feet) below the surface, left for the site Sunday. He gave no further details. 
 
 Making his first public comments since the crash of the Airbus A320 while en route from Paris to Cairo, el-Sissi says it "will take time" to determine the exact cause of the crash, which killed all 66 people on board. 
 
 He thanked the nations that have joined Egyptian navy ships and aircraft in the search for the wreckage and started his comments with a minute of silence in remembrance of the victims. 
 
 El-Sissi also cautioned the media against premature speculation on the cause of the crash. 
 
 "There is not one scenario that we can exclusively subscribe to ... all scenarios are possible," he said. 
 
 El-Sissi spoke a day after the leak of flight data showing trouble in the cockpit and smoke in a plane lavatory aboard the doomed aircraft, bringing into focus the chaotic final moments of the flight, including a three-minute period before contact was lost as alarms on the plane screeched one after another. 
 
 Officials have been cautioning that it was still too early to say what happened to the aircraft, but mounting evidence points to a sudden, dramatic catastrophe that led to the crash. 
 
 Egypt's military on Saturday released the first images of aircraft debris plucked from the sea, including personal items and damaged seats. Egypt is leading a multi-nation effort to search for the plane's black boxes and other clues that could help explain its sudden plunge into the sea. 
 
 "If they lost the aircraft within three minutes that's very, very quick," said aviation security expert Philip Baum. "They were dealing with an extremely serious incident." 
 
 Authorities say the plane lurched left, then right, spun all the way around and plummeted 38,000 feet (11,582 meters) into the sea — never issuing a distress call. 
 
 Investigators have been poring over the plane's passenger list and questioning ground crew at Paris' Charles de Gaulle airport, where the airplane took off. Beside Egypt, ships and planes from Britain, Cyprus, France, Greece and the United States are taking part searching a wide area of sea 180 miles (290 kilometers) north of the Egyptian port city of Alexandria. 
 
 The EgyptAir tragedy deepens the country's struggle to revive its battered economy. While it may not reflect directly on security at Egypt's airports — which has been under international scrutiny since a Russian airliner crashed in the Sinai Peninsula in October after taking off from an Egyptian resort — the country's association with yet another air disaster will further damage its vital but currently depressed tourism industry. ||||| PARIS/CAIRO (Reuters) - The EgyptAir jet which crashed in the Mediterranean on Thursday sent a series of warnings indicating that smoke had been detected on board, shortly before it disappeared off radar screens, French investigators said on Saturday. 
 
 A spokesman for France’s BEA air accident investigation agency said the signals did not indicate what caused the smoke or fire on board the plane, which plunged into the sea with 66 people on board as it was heading from Paris to Cairo. 
 
 But they offered the first clues as to what unfolded in the moments before the crash. 
 
 One aviation source said that a fire on board would likely have generated multiple warning signals, while a sudden explosion may not have generated any - though officials stress that no scenario, including explosion, is being ruled out. 
 
 Egypt said its navy had found human remains, wreckage and the personal belongings of passengers floating in the Mediterranean about 290 km (180 miles) north of Alexandria. 
 
 The army published pictures on Saturday on its official Facebook page of the recovered items, which included blue and white debris with EgyptAir markings, seat fabric with designs in the airline’s colors, and a yellow lifejacket. 
 
 Analysis of the debris and recovery of the plane’s twin flight recorders are likely to be key to determining the cause of the crash - the third blow since October to Egypt’s travel industry, still reeling from political unrest following the 2011 uprising that ousted Hosni Mubarak. 
 
 A suspected Islamic State bombing brought down a Russian airliner after it took off from Sharm el-Sheikh airport in late October, killing all 224 people on board, and an EgyptAir plane was hijacked in March by a man wearing a fake suicide belt. 
 
 A message purporting to come from Islamic State urged attacks on the United States and Europe in the Islamic holy month of Ramadan beginning in early June. “Ramadan, the month of conquest. Get prepared...so that you make it a month of calamity on the non-believers anywhere,” said the message posted on Twitter accounts that usually publish Islamic State statements. 
 
 It made no claim of responsibility for the Egyptair crash. 
 
 The October crash devastated Egyptian tourism, a main source of foreign exchange for a country of 80 million people, and another similar incident would crush hopes of it recovering. 
 
 Egypt’s tourism revenue in the first three months of the year plunged by two thirds to $500 million from a year earlier. 
 
 HUNT FOR BLACK BOXES 
 
 The signals from the plane “do not allow in any way to say what may have caused smoke or fire on board the aircraft”, said a spokesman for the French BEA agency, which is assisting an official Egyptian investigation. 
 
 He added that the priority now was to find the two flight recorders, known as black boxes, containing cockpit voice recordings and data readings, from the Airbus A320 which vanished from radar early on Thursday. 
 
 Recovered debris of the EgyptAir jet that crashed in the Mediterranean Sea is seen in this handout image released May 21, 2016 by Egypt's military. Egyptian Military/Handout via Reuters 
 
 the head of the Egyptian investigation team was quoted by Egypt’s state-owned Al-Ahram newspaper as saying a preliminary report into the crash would be presented in a month. 
 
 Civil Aviation Minister Sherif Fathi told reporters an additional challenge in the hunt for the black boxes was the depth of the Mediterranean in the area under search. “What I understand is that it is 3,000 (meters),” he said. 
 
 That would place the black box locator beacons, which last for 30 days, on the edge of their detectable range from the surface based on the type of acoustic equipment typically used during the first stages of a search, according to a report into the 2009 crash of an Air France jet in the Atlantic. 
 
 “No important devices from the plane have been retrieved so far,” Fathi said. 
 
 The flight data transmitted before the crash was sent through an automatic system called the Aircraft Communications Addressing and Reporting System (ACARS), which routinely downloads maintenance and fault data to the airline operator. 
 
 Aviation Herald, a respected Austria-based website specializing in air accidents, first published a burst of seven messages broadcast over the space of three minutes. These included alarms about smoke in the lavatory as well as the aircraft’s avionics area, which sits under the cockpit. 
 
 While suggesting a possible fire, the relatively short sequence of data gives no insight into pilot efforts to control the aircraft, nor does it show whether it fell in one piece or disintegrated in mid-air, two aviation safety experts said. 
 
 The data fragments also included alarms related to cockpit window heating and two flight control computers, both of which have backups. 
 
 “The question now is whether the fire that caused the smoke was the result of an electrical fault - for example a short-circuit caused by damaged wiring - or whether some form of explosive or incendiary device was used - for example by a terrorist - to generate a fire or other damage,” aviation safety expert David Learmont said. 
 
 The ACARS data suggested the fire had spread quickly and “that might explain the fact that there was no distress call”, Learmont wrote in a blog. 
 
 “ALL SCENARIOS” POSSIBLE 
 
 The aircraft was carrying 56 passengers, including a child and two infants, and 10 crew. They included 30 Egyptian and 15 French nationals, along with citizens of 10 other countries. 
 
 Egyptair said officials met family members and told them the process of gathering body parts and information would take time, while DNA testing to identify victims would require weeks. 
 
 French Foreign Minister Jean-Marc Ayrault, who met relatives of crash victims in Paris on Saturday, said there were several possible causes. “At this very moment all scenarios are being examined and none is being given greater emphasis,” he said. 
 
 France sent a plane and navy ship to help the search, centered on an area just south of where the signal from the plane was lost early on Thursday. 
 
 Slideshow (17 Images) 
 
 EgyptAir Chairman Safwat Moslem said the radius of the search zone was 40 nautical miles, but could be expanded. The radius is equivalent to an area of 5,000 square miles (17,000 square km), the same expanse covered in the initial hunt for the Air France jet in 2009. 
 
 The large area reflects the fact that neither jet could be accounted for in the last few minutes of flying time. 
 
 A European satellite spotted a 2 km-long oil slick in the Mediterranean, about 40 km (20 nautical miles) southeast of the aircraft’s last known position, the European Space Agency said.
– Smoke was detected in multiple places on EgyptAir Flight 804 moments before it plummeted into the Mediterranean, but the cause of the crash that killed all 66 on board remains unclear, the French air accident investigation agency says. Agency spokesman Sebastien Barthe tells the AP that the plane's automatic detection system sent messages indicating smoke a few minutes before the plane disappeared from radar while flying over the eastern Mediterranean early on Thursday morning. The messages, he says, "generally mean the start of a fire," but he adds: "We are drawing no conclusions from this. Everything else is pure conjecture." The aircraft had been cruising normally in clear skies early Thursday when it suddenly lurched left, then right, spun all the way around, and plummeted 38,000 feet into the sea. Aviation experts have said the erratic flight suggests a bomb blast or a struggle in the cockpit. But so far no hard evidence has emerged. Search crews found floating debris and human remains on Friday, and photos posted on the Facebook page of Egypt's chief military spokesman appear to show the remains of plane seats, life jackets, and a scrap of cloth that looks to be part of a baby's blanket. Search crews from Egypt and five other countries—Greece, Britain, France, the US, and Cyprus—are searching a wide area of the eastern Med for further wreckage.