Hamas gunmen killed five of their own combatants in an ambush on a Fatah vehicle that had been carrying Hamas detainees, Fatah officials said Wednesday.
Also killed were two members of the Fatah-affiliated Preventive Security force that had been guarding the detained Hamas members, the officials said.
The exact circumstances of the incident were not immediately clear. Hamas radio reported that a Hamas man was killed in another clash.
Four days of intense Palestinian infighting in the Gaza Strip has killed 41 people.
Early Wednesday morning, Hamas gunmen executed six Fatah bodyguards as the Gaza Strip slid further into chaos.
The streets of central Gaza City echoed with the rattle of machine gun fire, and were empty except for gunmen in black ski masks. Terrified residents huddled in dark homes after electricity to some downtown neighborhoods was cut off by a downed power line.
A nurse traveling in an ambulance was shot in the head and killed after being caught in the crossfire, hospital officials said.
Fighting raged close to Palestinian Authority Chairman Mahmoud Abbas's heavily guarded compound, which was also targeted by Hamas mortar fire overnight. Abbas was not present.
Early Wednesday, Hamas gunmen fired mortars and pipe bombs at the home of Fatah security chief Rashid Abu Shbak, before storming inside, lining six Fatah bodyguards up against the wall and shooting them dead, Palestinian security and medical officials said.
Hamas claimed that it men only stormed the home after the bodyguards fired at them.
Abu Shbak and his family were not home at the time of the attack, but the house was guarded by at least a dozen of his guards.
Abdel Hakim Awad, a Fatah spokesman, angrily accused Hamas's leadership of the attack on Abu Shbak's house.
"All (Hamas) are killers from top to bottom, all are implicated," he said, charging that the Islamist group "wanted to turn Gaza into a new Somalia or Darfur."
Late Tuesday night, PA Prime Minister Ismail Haniyeh announced that a new cease-fire deal had been reached between the rival Fatah and Hamas factions.
The truce, which began at 2 a.m., followed yet another day of bloody clashes between Fatah and Hamas militiamen in Gaza, in which least 20 Palestinians were killed and 70 were wounded.
As per the terms of the agreement, all gunmen were ordered to leave the streets in the Gaza Strip, and all Palestinian abductees were to be released.
Shortly after the cease-fire was announced, however, gunmen fired from a passing car at members of an Egyptian delegation who were in Gaza to mediate between the two sides. No one was wounded in the incident.
Meanwhile, Palestinian leaders said Tuesday that Hamas was trying to divert attention from internecine fighting in the Gaza Strip by firing dozens of Kassam rockets at Israel. The group wants to drag Israel into the conflict to embarrass the Palestinian Authority and bring about its collapse, they added.
Earlier, appeals by many Palestinians and Arab governments fell on deaf ears as gunmen continued to fight street battles in different parts of the Gaza Strip.
In addition, most Palestinians ignored appeals from hospitals for blood donations.
"The streets are completely deserted and people are afraid to walk out of their homes," said a local journalist. "This is a real war and people are really afraid."
Hundreds of Fatah and PA policemen surrounded the Islamic University in Gaza City - a stronghold of Hamas - and threatened to storm the premises. Hamas warned that its men would turn the university complex into a "graveyard" for the attackers if they carried out their threat.
Hamas militiamen fired several missiles at the headquarters of the PA General Intelligence Service in the northern Gaza Strip. The movement also threatened to destroy the offices of PA Chairman Mahmoud Abbas in Gaza City.
Tuesday's clashes began when Hamas gunmen killed eight PA security officers near the Karni border crossing. A ninth officer was shot and killed by IDF soldiers as he tried to escape toward the border with Israel.
Fatah and PA officials denounced the attack as a massacre and vowed to avenge the killings.
Fatah legislator Jamal Abu Rub said Hamas and the IDF were responsible.
"The time has come for our people to realize that there is a huge conspiracy by mercenaries to destroy the Palestinian Authority," he said. "The security situation in the Gaza Strip is intolerable. We can't remain idle in the face of the atrocities committed by Hamas and Israel."
Fatah's armed wing, the Aksa Martyrs Brigades, warned Hamas against targeting Abbas and other senior PA figures. Leaflets distributed by the group in Gaza said Hamas would pay a heavy price if it dared to target PA leaders.
In response to the incident near the Karni border crossing, four Fatah legislators announced they were suspending their membership in the Palestinian Legislative Council, demanding an immediate halt to the infighting. They threatened to resign if the fighting continued. They also urged Palestinians to take to the streets to express their outrage at the ongoing violence.