The United Nations is warning of a “grave and desperate” crisis inside a massive camp for Palestinian refugees overrun by the Islamic State in Syria. Islamic State fighters are now in control of most of Yarmouk after entering last week. There are reports of scores of dead residents, including by beheading. Hundreds of people have reportedly fled. Pierre Krähenbühl, the head of the U.N. agency for Palestinian refugees, issued a global appeal.

Pierre Krähenbühl: “(The situation) has never been as grave and desperate as it is now in Yarmouk Camp. It is a place that has been besieged for two years, where about 18,000 people have been surviving on very minimal assistance for a long time. And now, with the fighting intensifying, their lives are in immediate danger. I think here not only that there are the 18,000 civilians, but there are 3,500 children among them. And with the intensity of the confrontations, our call has been for parties to immediately suspend military operations that put civilians in danger.”

Yarmouk has been under siege by the Assad regime for nearly two years and repeatedly stuck in the crossfire of Syria’s civil war. With control of Yarmouk, ISIS is just a few miles from the center of the Assad regime’s Damascus stronghold. A Palestinian militia has clashed with ISIS fighters in defense of the camp. But the al-Qaeda-linked Jabhat al-Nusra has prevented other armed groups from reinforcing the fighters battling ISIS. According to The Wall Street Journal, wounded al-Nusra fighters have recently been treated in Israeli hospitals across the border as part of an apparent Israeli effort to tacitly back Sunni fighters opposed to Iran.