The United Nations yanked its refugess mission from Gaza after three masked Palestinian gunmen opened fire at a vehicle carrying the chief of the mission and tried to kidnap him, sources tell FOX News.

Gunmen blocked the car of mission chief John Ging, head of U.N. Relief and Works Agency for Palestinian Refugees, and fired 11 bullets at his car as he tried to drive off.

The United Nations told all foreign staff members to leave Gaza immediatly, a U.N. source told FOX News.

Ging said no one was hurt in the kidnap attempt in northern Gaza.

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.

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"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.

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.

Earlier in the week, unidentified gunmen abducted a BBC reporter in Gaza City. The reporter, Alan Johnston, remained in captivity on Friday.

In the past 18 months, more than a dozen foreign journalists and aid workers have been abducted in Gaza, an area plagued by crime, political violence and lawlessness. Most of the kidnappings have been carried out by gunmen seeking favors from the government or trying to settle scores with rivals.

In most cases, victims have been released unharmed within hours.

The Associated Press contributed to this report.