The Palestinian militant group Hamas has vowed revenge for the latest killing of its members by Israel. Palestinian officials say such targeted attacks will only undermine their efforts to clamp down on militants.

Hamas spiritual leader Sheikh Ahmed Yassin was quoted by Israel Radio as saying that Israel will pay the price for, what he called, Sunday's "murder."

The missile strike in Gaza City came just hours after Israeli army chief Moshe Yaalon said all leaders of Hamas are targets for assassination. He also vowed that Israeli forces will take action against Islamic militant groups if Palestinian security forces do not.

Among those killed were two members of Ezzedine al-Qassam, the military wing of Hamas, the group responsible for the suicide bombing on a bus in Jerusalem last week that killed 21 people.

The Palestinian Authority says the strike will only hurt its efforts to rein in militants. The attack was carried out not long after Palestinian security officials ordered forces to prevent rocket and mortar attacks against Israelis.

Late Saturday, Palestinian security forces shut down several tunnels used by militants to smuggle weapons to Gaza from Egypt.

At least nine people were arrested during the raids.

Palestinian militant groups last week called off their June 29th agreement to stop attacking Israelis, as both sides renewed violent attacks that began in a Palestinian uprising nearly three years ago.

On Thursday, Israeli helicopters fired at a car in Gaza City killing Ismail Abu Shanab and two other Hamas members.

Before the latest attack in Gaza, members of the Palestinian Cabinet proposed that the Palestinian militant groups agree to a new truce on condition that Israel was also bound to the agreement.

Israeli officials immediately rejected the idea, saying that the Palestinian Cabinet must first disarm and dismantle Islamic and other militia groups.