In a stretch of desert in southern Syria on the border with Jordan, a sandstorm battered the shelters of some 50,000 displaced people in a makeshift camp already running low on food, clean water and medical care.

The weather is only one of many concerns for the increasingly desperate families in Rukban camp. The United Nations warned that humanitarian conditions have reached a critical level and aid groups are scrambling to reach the area.

A convoy is scheduled to reach Rukban on Thursday after receiving clearance from the Syrian government. But a long-term plan for relief remains elusive.

The camp sprang up in a demilitarized zone between the two countries as tens of thousands of people fled the devastation of war in Syria — many from areas where Russian- and American-backed forces were fighting the Islamic State. They found themselves blocked from entering Jordan.