Rival Palestinian factions have clashed for the fourth straight day in the Gaza Strip. At least 16 Palestinians were killed, bringing the death toll to at least 40 since Friday. As Robert Berger reports from VOA's Jerusalem bureau, Palestinian militants also launched a wave of rocket attacks against Israel.

A Palestinian security force officer stands in the damaged house of Fatah security chief Rashid Abu Shbak after it was attacked by Hamas militants in Gaza City, 16 May 2007

Hours later, policemen loyal to Fatah arrested five Hamas men, but as they drove them through town the vehicle was ambushed by Hamas fighters. Officials say five Hamas men in the car were killed, along with two more from Fatah.

Each side is blaming the other for the violence.

Hamas spokesman Fawzi Barhoum told Israel Radio that Fatah gunmen started the latest round of fighting when they ambushed a car carrying a senior Hamas official who had helped mediate a cease-fire.

The quick collapse of the third ceasefire in as many days has raised fears of civil war.

Palestinian Information Minister Mustafa Barghouti also said on Israel Radio that the public has lost confidence in the cease-fires. He warned that if Gaza turns into Somalia, the Palestinian cause will suffer a setback lasting for decades.

Hamas militants also fired rockets across the border, terrorizing the nearby town of Sderot. Israel responded with a rare air strike. But Israeli officials have ruled out a major assault on Gaza, saying it would unify the Palestinians and play into the hands of Hamas.