UN: 257 Palestinian children killed in Gaza

He said Israel gave no warning, unlike two years earlier when he received repeated calls from the Israeli military, including on his cell phone, that a nearby house was going to get hit and that he should evacuate.

Smoke rises during Israeli's offensive in Gaza January 8, 2009. Palestinians faced even grimmer conditions in the Gaza Strip on Thursday after a UN aid agency halted work, saying its staff were at risk from Israeli forces fighting Hamas militants, after two drivers were killed. [Agencies]

"What's going on is not a war, it's a mass killing," said Abu Aisheh, still wearing the blood-splattered olive-colored sweater he wore the night of the airstrike.

The Israeli military did not comment when asked why the Abu Aisheh house was targeted.

In the Zeitoun neighborhood of Gaza City, medics found four young children next to their dead mothers in a house, according to the Geneva-based International Committee of the Red Cross. "They were too weak to stand up on their own," the statement said.

The Red Cross did not say what happened to the children, but noted that the Israeli army refused rescuers permission to reach the neighborhood for four days. Israel said the delay was caused by fighting.

Medic Mohammed Azayzeh said he retrieved the bodies of a man and his two young sons from central Gaza on Wednesday. One of the boys, a 1-year-old, was cradled in his father's arms.

In the Jebaliya refugee camp, five sisters from the Balousha family, ages 4, 8, 11, 14 and 17, were buried together in white shrouds on December 29. An Israeli airstrike on a mosque, presumably a Hamas target, had destroyed their adjacent house. Only their parents and a baby girl survived.

Israel accuses Hamas of cynically exploiting Gaza's civilians and using them as human shields. The military has released video footage showing militants firing mortars from the rooftops of homes and mosques.

"Israel wants to see no harm to the children of Gaza," said Israeli government spokesman Mark Regev. "On the contrary, we would like to see their children and our children grow up without the fear of violence. Until now, Hamas has deliberately prevented that from becoming reality."

Rocket fire from Gaza has disrupted life in Israeli border communities, and with the latest intensified militant attacks, hundreds of thousands of Israelis are in rocket range. Schools are closed and fearful Israeli children rush into bomb shelters at the sound of air raid sirens.