Gaza City, Gaza Strip ? Three masked Palestinian gunmen opened fire Friday on a vehicle carrying the chief of the U.N. refugee mission in Gaza and tried to kidnap him, the U.N. official said.

John Ging, head of the U.N. Relief and Works Agency in Gaza, said no one was hurt in the kidnap attempt in northern Gaza, but in the wake of the attack, the mission would consider sending home foreign staffers.

Ging, a driver and a security official were traveling in an armored vehicle when the gunmen jumped out of a white Subaru and opened fire, he said.

“They tried to force open the car, but our driver extracted himself from that situation,” and sped away as the gunmen continued firing, he said.

Eleven bullets pierced the vehicle, which was clearly marked with the U.N. insignia and a U.N. flag, Ging said. The incident took place about half a mile from the Erez passenger crossing into Israel, he added.

No one claimed responsibility for the attack.

Michele Montas, a U.N. spokeswoman in New York, said Ging was traveling in a three-car U.N. convoy.

UNRWA has about 11,000 staffers operating in the Gaza Strip, the overwhelming majority of them Palestinians. The mission includes eight foreigners, and at a news conference after the attack, Ging said his agency would consider scaling back its foreign staff.

Because the vehicles that were fired upon were so clearly marked, there are “some very serious security implications for us and for our staff,” he said. Backup staff from overseas will not be brought in, and the agency will “review the necessity for the staff that are here at the moment,” he said.