Thousands of families fleeing a Syrian government offensive in the southern city of Dara’a were stranded at the Jordanian border on Saturday, unable to either return home or escape the violence because passageways to the neighboring country had been sealed.

The situation was quickly deteriorating at several spots along the border with no shelter, running water or sanitary facilities, according to aid organizations and activists in the area. Humanitarian organizations have called on Jordan to open the border to Syrians fleeing violence.

The new offensive by Syrian government forces aims to regain control of one of the country’s last two rebel-held territories. It has driven thousands from the city, which is just a few miles from a border crossing into Jordan. But Jordan closed its border with Syria two years ago after a car bomb in June 2016 killed seven Jordanian border guards.

Jordan and Syria’s other neighbors, Lebanon and Turkey, have borne the brunt of the exodus of millions of refugees who have fled across the borders during the past seven years of war. The conflict has displaced nearly 12 million people, more than half of Syria’s population.