UNITED NATIONS - Israeli attacks in Gaza are taking a horrifying toll on civilians already suffering dwindling food supplies and looting due to the aid blockade, UN humanitarians said on Thursday.

The UN Office for the Coordination of Humanitarian Affairs (OCHA) said that there have been daily reports of Israeli strikes killing and injuring many Palestinian civilians.

"Just yesterday (Wednesday) in Gaza City, there were reports of dozens of people killed, including at least eight children, after an Israeli strike hit a residential building," OCHA said. "Many are still missing under the rubble."

The Ministry of Health in Gaza reported that more than 1,500 people reportedly were killed, many of them women and children, since the intensification of hostilities less than a month ago.

The office said the hostilities and continued blocking of cargo entry into Gaza for almost six weeks are hampering people's access to life-saving aid.

"As supplies inside the Strip near exhaustion and the situation becomes increasingly dire, there has been an increase in looting over the past few days," OCHA said. Earlier this week, several such incidents were reported in Rafah, Deir al Balah and Al Zawaida.

OCHA reiterated the urgency of reopening the crossings to allow critical supplies to enter.

More than 60,000 children are reportedly suffering from malnutrition at a time when community kitchens are rapidly running out of fuel and supplies.

The World Health Organization (WHO) said it has been able to support some medical evacuations from Gaza. On Wednesday, 18 patients and nearly 30 companions were allowed to leave for specialized treatment abroad.

However, with some 12,500 patients in Gaza still in need of medical evacuation outside the strip, WHO called for evacuations through all available border crossings and corridors.

Across Gaza, OCHA said its partners are warning of acute water shortages in shelters hosting displaced people. The loss of water, the lack of cleaning supplies and cohabitation with livestock are having a dire public health impact. In March, more than one-third of households in Gaza experienced lice infestations.