A crowd sifted through the rubble of a home in the Bureij refugee camp near Gaza City that was flattened by a massive explosion. Palestinian officials say the attack killed senior Islamic Jihad commander Ayman al-Fayed, his wife and two young children and four other militants.
Islamic Jihad said the blast was caused by an Israeli air strike.
Islamic Jihad spokesman Abu Ahmed promised retaliation for what he called a massacre. He said the Palestinian people would strike at the Israeli enemy everywhere.
While Israel has vowed to target the leadership of militant groups in response to daily rocket attacks from Gaza, the Israeli army says it was not involved in the incident. Witnesses saw rocket parts at the scene, indicating that explosives in the house might have blown up by accident.
Palestinian militants fired rockets at Israel in response to the killing and vowed that there is more to come. Israel is threatening to launch a large-scaled ground offensive in Gaza if the rocket attacks continue.