TEHRAN, Iran (CNN)  -- An Iranian airliner that crashed Wednesday, killing all 168 passengers and crew, plunged into the ground and disintegrated on impact, according to a security official.



Debris from the plane was littered around the crash site.



Images of the crash site show a smoldering crater scattered with charred pieces of the plane and tattered passports.



Ten members of the country's youth judo team were aboard the Caspian Airlines plane, said several sources, including Iran's Press TV. The government-backed network said the dead included eight athletes and two coaches.



The plane "disintegrated into pieces," said Col. Masood Jafari Nasab, security commander of Qazvin, the city nearest to the crash site in northwestern Iran.



"The aircraft all of a sudden fell out of the sky and exploded on impact, where you see the crater," a witness told Press TV from the crash site.  Watch images of the crash site »



The plane's flight data recorder and cockpit voice recorder have been found, state television reported late Wednesday.



The crash was at least the fifth major airline accident in the world this year, following crashes of planes flown by Colgan Air, Turkish Airlines, Air France and Yemenia Airways. A US Airways pilot managed to land his plane safely on the Hudson river in New York City in January, with no major injuries, after the plane lost power.



But aviation safety expert John Wiley said there is no reason to fear air travel in general, and no single airline or aircraft is particularly dangerous.



The three most recent crashes -- in which a total of 548 people died -- involved different planes, flown by different airlines, in different stages of flight, he said.



Caspian Airlines Flight 7908 -- a Russian-made Tupolev Tu-154M plane -- went down near the village of Jannatabad near Qazvin at 11:33 a.m. (2:03 a.m. ET) Wednesday, Press TV reported.



Conversations between the pilot and the ground were normal and did not indicate any technical problems, the network's Web site reported, citing the managing director of Iran's airport authority without naming him.



Some witnesses say the plane caught fire before crashing, Press TV said.



The plane descended very quickly, Wiley told CNN, but it may have been circling, trying to land, rather than plummeting to the ground.



Qazvin Police Chief Hossein Behzadpour and Mohammad Reza Montazer Khorasan, the head of the disaster management center in Iran's health ministry, both confirmed that all 168 people on board died, Press TV reported.



The U.S. State Department, in a statement, extended its condolences to the victims. Department spokesman Ian Kelly said officials were working to determine whether any Americans were on board.



Aviation analyst Kieran Daly told CNN that many aircraft operating in Iran are aging Tupolevs, some dating back to the 1970s.



He described Tupolevs as "workhorses of the old Soviet aviation system."



But he said the Caspian Airlines fleet is based on a slightly newer design, dating to the late 1980s and early 1990s.



Pictures from the scene were "consistent with a high-speed impact," he said. But he added that there could be large debris not seen on television, and that could change his analysis.  Watch Daly talk about the crash »



A team of investigators from the Russian Interstate Aviation Committee is flying to the crash scene to join the investigation, the agency said in a posting on its Web site. They will work alongside Iranian aviation authorities, the agency said.



An agency official declined to comment further, saying the plane was operated by an Iranian company and nothing is known about it.



A Tupolev representative told CNN the manufacturer will not comment until the aviation committee releases its report on the crash.



The Tupolev 154 is essentially banned in the West because it does not comply with European noise and pollution regulations, but it has a safer-than-average accident record, Wiley said.



Wednesday's crash is the first on record for Caspian Airlines, which was founded in 1993, he added.



The Iranian newspaper Hamshahri reported
Did they find the data recorder? Where  did the plane crash? How many are believed to be dead in the Iranian plane crash? How many died? What does state TV report?
have been found, state television reported late Wednesday. in northwestern Iran. all 168 passengers killing all 168 passengers and crew, Ten members of the country's youth judo team were aboard the Caspian Airlines plane,
question: Did they find the data recorder?, answer: have been found, state television reported late Wednesday. | question: Where  did the plane crash?, answer: in northwestern Iran. | question: How many are believed to be dead in the Iranian plane crash?, answer: all 168 passengers | question: How many died?, answer: killing all 168 passengers and crew, | question: What does state TV report?, answer: Ten members of the country's youth judo team were aboard the Caspian Airlines plane,