UNITED NATIONS — Palestinian children are dying at a heavy rate in the Israeli-Hamas fighting — about one of every three persons killed, according to Gaza statistics.

As of Thursday, 257 children were among the approximately 760 reported dead in Gaza. There were another 1,080 children among the 3,100 injured in the conflict, according to statistics from Gaza's health ministry. The U.N.'s top humanitarian official, John Holmes, described the numbers as "credible" and deeply disturbing. U.N officials say about half of the casualties were civilians.

Holmes and John Ging, head of Gaza operations for the United Nations Relief and Works Agency, both expressed anger and regret at their decision Thursday to temporarily suspend aid shipments in the Gaza Strip because it was too risky for their aid workers.

Ann Veneman, executive director of the U.N. children's agency, UNICEF, warned the suspension of aid would put children even more in harm's way.

The Israeli military said in a statement that it cooperates closely with foreign aid groups to help civilians, and said Hamas uses civilians as human shields.

The decision to suspend aid deliveries in Gaza came after Israeli strikes killed two drivers for UNRWA and injured a third in marked vehicles, U.N. officials say. In all, four of UNRWA's Gaza staff have been killed since Israel launched a major attack on Hamas 13 days ago.

The World Health Organization said Gaza's health services were "on the point of collapse" — the hospitals overwhelmed, health care workers exhausted. It said the dead included 21 medical personnel, 30 more were injured and 11 ambulances have been hit.