GAZA CITY, Gaza Strip - Israeli aircraft fired on militant targets in Gaza City in predawn airstrikes Sunday, hours after Palestinian gunmen breached Israel's heavily fortified Gaza border and tried to capture an Israeli soldier.

Palestinians sift through the rubble of a destroyed office of the Islamic Jihad group, after it was hit by an Israeli missile strike in Gaza City, Sunday, June 10, 2007. [AP]

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.

The fighting between Israel and the Palestinians pre-empted clashes between the Palestinians' two ruling parties, Hamas and Fatah, that broke out in mid-May and left more than 50 Palestinians dead. A truce declared two weeks ago was meant to end the bloodletting, but last week the fighting reignited around the southern Gaza city of Rafah. Three militants have been killed in fighting since Thursday.

Fatah and Hamas gunmen battled in Rafah late Saturday, with the shootouts spilling into early Sunday and spreading from the city's western neighborhoods into the east. Snipers took positions on buildings, and rival factions set up roadblocks meant to help them identify and target enemy fighters, witnesses said.

Bullets flew, and militants launched rocket-propelled grenades as the fighting heated up.

One clash took place near the house of Ghazi Hamad, the spokesman of Prime Minister Ismail Haniyeh of the Islamic militant Hamas, but his home was not attacked, his wife said.

Roads to and from one neighborhood that has been the site of fierce fighting were shut down, witnesses said.

Palestinian officials reported 60 people injured in the overnight clashes.