(CNN) -- An Egyptian-brokered truce ended within hours early Monday when shooting resumed between rival Hamas and Fatah militias, leaving two gunmen dead and 10 others wounded, Palestinian security sources said. Violence between the factions left four dead on Sunday.
According to the sources, the gunbattle broke out near the Fatah intelligence headquarters in northern Gaza City. The dead were the bodyguards of a local Fatah leader.
In protest of the ongoing violence in Gaza, Palestinian Interior Minister Hani al-Qawasmi resigned Monday, one of his assistants told CNN. According to the assistant, Prime Minister Ismail Haniyeh accepted al-Qawasmi's resignation.
Al-Qawasmi's resignation is a significant blow to the Palestinian unity government, formed earlier this year in an effort to end the deadly factional fighting concentrated in Gaza.
Two major sticking points in forming the Fatah-Hamas government were the portfolio of the interior minister and choosing who would fill the key position.
The interior minister has control of Palestinian security forces.
Amid frustrations over the inability to enact a Gaza security plan, al-Qawasmi had tendered his resignation to Haniya a few weeks ago, but the prime minister did not accept it.
Cease-fire broken before daybreak
Hamas and Fatah officials had told reporters shortly after midnight Monday that they would begin observing a cease-fire at 1 a.m. (6 p.m. Sunday ET), but the truce never made it to daybreak.
Under the agreement, all checkpoints were required to be dismantled, gunmen from both sides were required to be withdrawn from the streets and any hostages held by either side were to be released.
"In order to maintain national unity and preserve Palestinian blood, Hamas and Fatah leaders met and agreed to end the fighting and remove the checkpoints," Ayman Taha, a Hamas official, said.
Earlier Sunday, violence between the Palestinian factions Hamas and Fatah raged in Gaza, leaving four militants dead and several other people wounded, Palestinian sources said.
Two Hamas militants were killed in a firefight with Fatah militants outside a mosque in Gaza City, Palestinian security sources said.
Nine other Palestinians -- four Hamas militants and five bystanders -- were wounded in the fighting, the sources said.
Separately, a commander of the Al Aqsa Martyrs' Brigades -- Fatah's armed wing -- and his assistant were shot and killed in northern Gaza by an unknown gunman, Palestinian security sources said.
Fighting then broke out at the commander's funeral in Jabalya in northern Gaza, but there were no reports of casualties.
Palestinian security sources also reported that Fatah militants kidnapped Ali Sharif, a professor at the Islamic University of Gaza who has ties to Hamas.
Hamas claimed in a leaflet that it has kidnapped 70 Fatah members, Hamas sources said. Fatah did not immediately confirm the claim.
Last year, Hamas ended decades of Fatah rule by winning Palestinian elections.
After months of deadly clashes, the two sides met recently to build a new government aimed at ending the fighting.
CNN's Kevin Flower, Shira Medding and Waffa Munayyer contributed to this story.
