JERUSALEM (CNN) -- Israeli troops Thursday killed a Palestinian militant trying to cross into Israel from Gaza and wounded another, according to Palestinian security sources.



Israeli soldiers stand in front of the Kerem Shalom crossing Thursday on the Israel-Gaza border.



Three armed militants tried to infiltrate into Israel near the Kerem Shalom crossing along the southern Gaza border, according to the Israeli military.



Israel Defense Forces said it fired at the militants, hitting two of them. It was unclear what happened to the third.



In a separate operation, Israeli forces killed another Palestinian militant Thursday near Jabalya in northern Gaza, Palestinian security sources said. The militant was part of a group trying to launch a mortar shell, sources said.



On April 9, Palestinian militants infiltrated Israel through the Nahal Oz border crossing in northern Gaza and fired on the fuel terminal there, killing two Israeli civilian workers. In response, Israel halted already reduced fuel shipments to Gaza.



It restarted some shipments on Wednesday but shut down the terminal again Thursday because of Palestinian sniper fire, according to the Israeli military.



During the brief time the terminal was open, Israel sent 437,000 liters of diesel fuel and 93 tons of gas to Gaza via Nahal Oz, the only transit route for delivering fuel supplies to Gaza.



Israeli forces also clashed early Thursday with Palestinian militants in the West Bank village of Qabatiya, killing the local Islamic Jihad leader and his deputy, the Israeli military said.



Bilal Hamuda Machmud Zaalah and his deputy, Adin Machmud Hasani Avidot, were hiding in a vehicle when Israeli soldiers and security forces spotted them and surrounded the vehicle, the military said.



"After confirming that the two men were armed, forces fired at the wanted men, killing both," according to an IDF statement.



Israel blames Zaalah for attacks against Israeli forces in the West Bank town of Jenin as well as other planned strikes inside Israel.



But Palestinian medical sources and witnesses said Israeli forces surrounded a house around 3 a.m., ordering the two members of Islamic Jihad to surrender. The militants wouldn't come out, the sources said, and they died in an exchange of fire with the soldiers.



The violence came a day after Israeli airstrikes and ground battles with Palestinian militants in Gaza left 21 dead -- 18 Palestinians and three Israeli soldiers -- according to Palestinian security sources.



A Reuters cameraman and two bystanders were killed in an apparent airstrike near El Bureij refugee camp in central Gaza, according to Hamas security sources and Palestinian medical sources. Other civilians and Palestinian militants also were killed in an Israeli strike on El Bureij.



U.N. Secretary-General Ban Ki-moon, in a statement through his spokesman, said he's "gravely concerned at the escalation of violence in Gaza and southern Israel" on Wednesday.



"He condemns the reported civilian casualties among Palestinians, including children, during Israeli military operations, and calls on Israel to abide by its obligations under international humanitarian law and human rights law," the statement said.



"The secretary-general also reiterates his condemnation of rocket fire against Israeli civilian targets. He urges all parties to exercise restraint." E-mail to a friend
What country closes a fuel terminal on the Gaza border? What did Israel have to close that was on the Gaza border? Two Islamic jihad militants were killed where? What did Israel do after sniper fire? Israeli troops fired on who? Who did troops fire upon? What country is fighting against the Palestinians? Was anybody killed during the gunfight?
Israel terminal Qabatiya, shut down the terminal again Three armed militants Three armed militants Israel 18 Palestinians and three Israeli soldiers
question: What country closes a fuel terminal on the Gaza border?, answer: Israel | question: What did Israel have to close that was on the Gaza border?, answer: terminal | question: Two Islamic jihad militants were killed where?, answer: Qabatiya, | question: What did Israel do after sniper fire?, answer: shut down the terminal again | question: Israeli troops fired on who?, answer: Three armed militants | question: Who did troops fire upon?, answer: Three armed militants | question: What country is fighting against the Palestinians?, answer: Israel | question: Was anybody killed during the gunfight?, answer: 18 Palestinians and three Israeli soldiers