Israeli missiles slammed into Palestinian security targets in Gaza City Thursday, after a roadside bomb killed two Romanian laborers working for Israel in the Gaza Strip, witnesses said.

Israel Radio reported that three buildings belonging to the Palestinian Authority had been hit including the Palestinian national security headquarters, the head offices of Palestinian Authority Chairman Yasser Arafat's Fatah faction in the Rimal neighborhood of Gaza City, and the headquarters of the Palestinian police force in Gaza.

Palestinian sources are reporting 10 casualties five of them serious, Israeli radio says that six people have been wounded.

The attack followed a bomb blast set earlier in the day by Palestinians that killed two Romanian workers repairing an Israeli border fence in the Gaza Strip. On Wednesday, the bodies of two Israeli teenagers were found bludgeoned to death in a cave in the West Bank.

Palestinian police near the security headquarters called over loudspeakers to bystanders to evacuate the area in anticipation of more attacks, as ambulance sirens wailed.