PHOTO: Bomb Blast Rocks Gaza Junction, 4 Dead

Several Palestinians were wounded, medical officials said, including the son of top Hamas militant Khalil al-Hayya.

A bomb exploded next to a car used by the armed wing of Hamas in the Gaza Strip on Friday, killing two gunmen and two other Palestinians, including a girl, the ruling Islamist group and medical officials said.

The attack was the third of its kind since midnight, making for one of the biggest flare-ups in internal violence since Hamas routed the forces of Palestinian President Mahmoud Abbas's secular Fatah faction to seize control of Gaza a year ago.

Hamas has regularly accused Fatah, which still holds sway in the Israeli-occupied West Bank, of planning and carrying out attacks against its administration in Gaza. Fatah denies it.

Palestinian authorities did not immediately lay blame for Friday night's blast at a junction outside Gaza City, which was initially believed to have targeted a Hamas police parking lot.

The fourth fatality, a man, was not immediately identified. Several Palestinians were wounded, medical officials said, including the son of top Hamas militant Khalil al-Hayya. Among the casualties were also passersby on their way to the beach.

Gaza had been especially calm since an Egyptian-brokered ceasefire between Israel and Hamas took hold last month.

But the truce has stoked some tensions between Palestinian factions as Hamas has sought to prevent other groups from firing cross-border rockets at Israel.

An Israeli military spokeswoman said she had no knowledge of any Israeli involvement in the junction attack.

Earlier on Friday, bomb blasts rocked a cafe and a the home of Hamas politician Marwan Abu Rass in Gaza City. A passerby was killed outside the cafe.

Hamas Interior Ministry spokesman Ehab al-Ghsain accused Fatah of being behind the attack on Abu Rass's home, which caused no casualties. Fatah denied involvement.