Earlier Sunday, Hamas and Fatah gunmen fought in Gaza City's beachfront neighborhoods and around security compounds, ignoring renewed truce appeals and Arab mediation efforts. One man was killed, raising the death toll from three days of fighting to 26.

During the weekly cabinet meeting, Prime Minister Ehud Olmert commented on the violence past the past few days.

"The State of Israel is following this violence from the outside. We hope that the violence in Gaza amongst the Palestinians will cease, and that also the violence and terror against Israel will end completely," the prime minister said.

On Saturday, security forces loyal to Palestinian Authority Chairman Mahmoud Abbas suffered a major blow when a number of their headquarters fell into the hands of Hamas gunmen in the Gaza Strip.

Some of the security installations were completely damaged by fire while others were leveled by Hamas militiamen and their supporters. The attackers captured documents and equipment as residents rushed to loot the offices.

"This was the biggest attack of its kind on our security headquarters," a senior PA official told The Jerusalem Post. "Unfortunately, we didn't have enough forces to protect the buildings. We're very concerned that Hamas has taken over the security compounds and stolen many files."

The official said he was unaware of reports that dozens of PA security officers had defected to Hamas in the past three days. He dismissed as "lies" claims by Hamas that American and Israeli security experts were helping Abbas's forces.

Following three days of heavy fighting, Hamas and Fatah announced Saturday evening that they had reached another cease-fire agreement and urged their supporters to halt the clashes.

Palestinian officials confirmed that Abbas will meet this week with Syria-based Hamas leader Khaled Mashaal in another bid to end the violence and reach an agreement on the formation of a Palestinian unity government. The meeting, the officials said, will take place in either Saudi Arabia or Qatar, whose ruler phoned Abbas Saturday and invited him to an urgent meeting in Doha.

At least 26 Palestinians were killed and nearly 300 wounded in the armed clashes since Thursday, when Hamas gunmen attacked a convoy of vehicles that was allegedly carrying weapons and military equipment for forces loyal to Abbas.

Among the casualties were four children and a woman. Hospital officials, who appealed for blood donations, said 41 of the wounded are in critical condition.

The latest cease-fire - the ninth in the past two months - was reached with the help of Egyptian security officials based in the Gaza Strip. The seven-point deal calls for withdrawing all militiamen from the streets and rooftops, deploying PA policemen in troubled areas to impose law and order, releasing all those who were kidnapped by both sides and ending the war of words between the two parties.

The cease-fire, the second of its kind in the past few days, was reached during a meeting between Hamas and Fatah leaders in the Egyptian Representative Office in Gaza City.

Even after the agreement was announced, Fatah and Hamas gunmen continued to exchange gunfire in different locations of the Gaza Strip. Eyewitnesses said the fiercest fighting took place inside and around Gaza City's Shifa Hospital. One man was killed during the gunfights, and at least 10 people were wounded. Some 50 total were wounded in Saturday's violence.

Hamas said the attack on the convoy of trucks was aimed at thwarting an attempt to deliver US-supplied weapons to Abbas's forces. Hamas gunmen managed to seize some of the trucks, which entered the Gaza Strip from Egypt through the Rafah border crossing, after killing and capturing several members of Abbas's Presidential Guard who were escorting the convoy.

Hours later, hundreds of Presidential Guard officers stormed the Islamic University premises in Gaza City, killing a number of Hamas gunmen and setting many buildings on fire. A statement by the Hamas-controlled Islamic University said the library and several halls were destroyed, as well as a number of laboratories. University officials estimate the damage at more than $15 million.

PA security sources claimed that the raid on the university led to the discovery of various types of weapons, including rockets and rifles. Hamas, however, denied that its members had used the university to store weapons. Hamas officials said the real purpose of the attack was the belief that kidnapped IDF soldier Cpl. Gilad Shalit was being held in a basement beneath one of the campus buildings.

Khaled Halak, a spokesman for the university, said the fire was still raging inside the building on Saturday as fire engines were unable to reach it because of the continued fighting on the streets. He said the 20,000 students who were supposed to resume studies on Saturday after a two-week recess have been asked to stay away.

PA Prime Minister Ismail Haniyeh of Hamas accused Abass's forces of destroying and ransacking the university and urged the PA chairman to assume his responsibilities and stop such assaults on academic institutions. Haniyeh also announced that his government would allocate one million dollars to help repair the damage.

In response to the attack on the Islamic University, Hamas gunmen set fire to the offices of the Fatah-run Al-Quds University in Gaza City. The student union at the university condemned the attack as cowardly and murderous and accused Hamas's "Executive Force."