Four members of the same family - four-year-old twin boys and their parents - were killed in an Israeli air strike in Gaza on Monday, the Hamas Health Ministry said.
Israel had no immediate comment on the attack, one of more than 80 bombings during the day in the Hamas-ruled territory, where Israel launched an aerial offensive on Wednesday it says is intended to quell rocket fire at its cities.
Ashraf al-Kidra, spokesman for the Hamas Health Ministry in Gaza, wrote on his Facebook page an Israeli air strike in the Gaza town of Beit Lahiya had crushed the home of Fuad Hejazi, killing him, his wife and two sons.
Neighbours contacted by Reuters said Hejazi did not belong to any militant group, nor did any organisation claim him as one of their members.
Israeli media said nine members of another family killed in an attack on Sunday, the al-Dalu family, who were buried on Monday, may have been bombed accidentally.
Israel has long targeted sites in the town where Hejazi lived, a frequent launch site for rocket strikes at Israel in the past decade.
Israeli military officials also insist measures are taken to avoid civilian casualties, including the diversion of missiles fired from drones, or calling off attacks at the last minute.
According to Palestinian officials, more than half the 108 Gazans killed since Wednesday were civilians, among them, 27 children. Three Israelis have been killed and more than 60 injured in rocket salvoes fired from Gaza in this period.