Fighting in Gaza between the militant Islamist group Hamas and a clan allied to its political rival Fatah has left four dead, reports say.
Executive Force paramilitaries act as police in Hamas-controlled Gaza
At least 20 people were wounded in the battle in Gaza City which erupted when Hamas security forces tried to arrest members of the Heles clan.
Rocket-propelled grenades and heavy machine-guns were used in the fighting.
Correspondents say it is one of the fiercest clashes since Hamas took over Gaza by force in June.
Two of the dead were Hamas Executive Force security officers and two were from the Heles clan, Hamas spokesman Ihab al-Ghusain told the AP news agency.
Fighting broke out on Wednesday evening when Heles clan members opened fire on Hamas security forces, Mr Ghusain said.
A Fatah official said Executive Force officers were trying to confiscate a car that belonged to a clan member.
Palestinian Authority President Mahmoud Abbas's Fatah movement has its power base in the West Bank.
Armed clashes often break out along factional and family lines across the Gaza Strip although fighting has died down since members of the Fatah movement were ousted from Gaza by Hamas in June.