Israel announced its worst combat losses for more than a month on Wednesday after an ambush in the ruins of Gaza City, and faced growing diplomatic isolation as civilian deaths mounted and a humanitarian catastrophe worsened.

Intense fighting was under way both north and south Gaza, a day after the United Nations demanded an immediate humanitarian ceasefire. U.S. President Joe Biden said Israel’s “indiscriminate” bombing of civilians was costing international support.

Warplanes again bombed the length of Gaza and aid officials said the arrival of winter rain worsened conditions for hundreds of thousands sleeping rough in makeshift tents. The vast majority of Gaza’s 2.3 million people have been made homeless.

Israel had global sympathy when it launched a campaign to annihilate the Hamas militant group that controls Gaza after fighters stormed across the border fence on Oct. 7, killing 1,200 Israelis, mostly civilians, and seizing 240 hostages.

But since then, Israel has besieged the enclave and laid much of it to waste. Gaza’s health ministry said on Wednesday at least 18,608 people have been killed and 50,594 injured in Israeli strikes on Gaza since Oct. 7. Many thousands more are feared lost in the rubble or beyond the reach of ambulances.

In Rafah, in Gaza’s south where hundreds of thousands of people have sought shelter, the bodies of a family killed in an overnight air strike were being laid out in the rain in bloodied white shrouds, including several small children. One, the size of a newborn, was wrapped in a pink blanket.