Fighting between rival Palestinian militant groups, meanwhile, spread in the southern Gaza Strip, further weakening a shaky truce forged in the face of punishing Israeli air assaults.

The attack on the frontier post Saturday was the first incursion into Israel from Gaza since militants killed two soldiers and seized a third nearly a year ago. The captured soldier, Cpl Gilad Shalit, remains missing.

The military said troops shot dead one of the gunmen involved in the attack Saturday, but no soldiers were harmed. Palestinians said three other militants escaped back to Gaza.

Islamic Jihad and the Al Aqsa Martyrs' Brigades, a violent offshoot of Palestinian President Mahmoud Abbas' Fatah movement, claimed responsibility.

Abu Ahmed, a spokesman for Islamic Jihad, said the raiders meant to snatch a soldier but the attempt was foiled by Israeli helicopter gunships called in as reinforcements.

"The aim of the operation was to withdraw with the soldier in captivity," he said. "But the participation of Israeli helicopters prevented that."

The dead raider belonged to Islamic Jihad, he said.

The Israeli military struck back Sunday, firing missiles at a building used by Islamic Jihad officials and an arms workshop run by Fatah fighters, it said.

Palestinian security officials reported two injured in a third strike near another Islamic Jihad office, but the military said there had been only two air attacks.

Militants broke through the Israeli border at a point 15 miles north of the location of last year's raid. That raid and the capture of Shalit touched off a five-month Israeli military incursion in which hundreds of Palestinian militants and civilians were killed.

Israeli troops pulled out after a Nov. 26 truce was called, but that cease-fire collapsed last month under a hail of Palestinian rocket fire on southern Israel, which in turn triggered dozens of Israeli air strikes.

More than 60 Palestinians, most of them militants, and two Israeli civilians have been killed since the clashes resumed.