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