Fatah and Hamas have declared another truce, after violent clashes unraveled the previous three-day ceasefire and led to at least 17 deaths.
At one point, radio stations of the two groups had stopped broadcasting songs of national unity and instead replaced them with ones on fighting the enemy.
Only masked security officers were seen on the streets of Gaza Friday, which were sealed off by makeshift roadblocks of rubble and trash.
On Friday morning, 50 officers from Palestinian Leader Mahmoud Abbas' presidential guard surrounded the Hamas-led Interior Ministry and exchanged fire with Hamas gunmen guarding the building.
The violence escalated until Fatah militants stormed a Hamas stronghold, the Islamic University in Gaza City.
Hamas fighters later retaliated by attacking two buildings of the Al-Quds University in Gaza, affiliated with Fatah.
In other news:
- Two Fatah-affiliated security officers and two Hamas gunmen were killed in clashes in northern Gaza on Friday
- Outside Gaza City, Hamas militants launched mortar shells at a Fatah training base.
- Hamas gunmen blew up the pro-Fatah Voice of Labour radio station in the northern town of Jebaliya.
- A total of 183 people were wounded since Thursday afternoon, the Health Ministry reported.
The new violence came just three days after Egyptian mediators convinced the warring factions to agree to a truce.
However, the deal did not settle lingering disputes between the Islamic militant Hamas and the more moderate Fatah.
Both sides insisted on retaining their armed men and talks on forming a unity government that might end Western sanctions have fallen through.
The clashes began Thursday when Hamas gunmen ambushed an official convoy guarded by the Fatah presidential guard in the Bureij refugee camp and hijacked two trucks filled with tents, medical kits and toilets, security officials said. The United States and some Arab countries had pledged to give equipment and training to the security forces loyal to Abbas.
Col. Burhan Hamad, the head of the Egyptian security team in Gaza that brokered the truce, denounced the attack on the convoy as "unjustified" and angrily blamed Hamas.
Meanwhile, the violent Islamic Jihad called for an urgent meeting to resume cease-fire talks and the mufti of Gaza called for a truce, saying Muslims shedding Muslim blood is "taboo."
The fighting deteriorated as the four sponsors of the stalled Middle East peace process, the European Union, Russia, United Nations and United States, were to meet in Washington Friday to discuss the Western embargo against Hamas.
The latest clashes flared after Hamas accused Washington of trying to provoke a Palestinian civil war by granting US$86 million to bolster Fatah security forces.
More than 100 Palestinians have been killed in internal violence since Hamas won parliamentary elections last year and formed a Cabinet.
With files from The Associated Press