UNITED NATIONS -- The UN Office for the Coordination of Humanitarian Affairs (OCHA) said Wednesday that the humanitarian crisis in Gaza has reached an unprecedented point.

The UN Agency for Palestine Refugees, or UNRWA, which is by far the largest humanitarian provider in Gaza, warned that the agency will be forced to halt all operations by Wednesday night unless fuel is allowed into Gaza immediately.

Hospitals are shutting down as they lack fuel, water, medical supplies and personnel. Fuel is being severely rationed for a select number of critical facilities. The backup generators are not designed for continuous operation and could break, said OCHA.

UN personnel visited hospitals on Tuesday. In one hospital, they noted hundreds of wounded men, women and children. Many of them were unconscious, with open wounds - lying on beds, stretchers and on the floor - with limited medical attendance. In the yard, there was a tent with tens of dead bodies, including children. Many of the dead are kept there because the morgues are full, it said.

Food stocks are running out. The World Food Programme estimates that current supplies of essential food in Gaza are sufficient for about 12 days. However, at shops, the available stock is expected to last for only five days, said OCHA.

People are resorting to drinking well water, which is extremely high in salt and poses immediate health risks. Health partners have also detected cases of chickenpox, scabies and diarrhea due to poor sanitation conditions and consumption of water from unsafe sources, it said.

The number of internally displaced people is now estimated at more than 1.4 million, including nearly 590,000 people sheltering in UNRWA-designated shelters. More than 15 percent of the displaced are estimated to have disabilities, yet most shelters are not adequately equipped for their needs, it said.

Local authorities report that more than 40 percent of all housing units in the Gaza Strip have been destroyed or damaged, said OCHA.