Masked Palestinian militants fired a rocket-propelled grenade at a vehicle from the Hamas armed force in northern Gaza, wounding five Hamas men inside, Hamas officials said.
It was not immediately known who the attackers were, but Palestinians said this was probably part of the months-long conflict between Hamas and the rival Fatah of Palestinian President Mahmoud Abbas. At least 62 people have been killed in the clashes.
Hospital officials said two of the wounded were in critical condition.
The attack took place in the Jebaliya refugee camp next to Gaza City, Hamas said.