Fighters supporting dictator Bashar al-Assad have displaced up to 50,000 and shut down at least three hospitals in a siege to retake a rebel-held region in southwest Syria that borders Jordan and the Israeli-occupied Golan Heights, the United Nations and a monitor group report this week.

“Over the past week, nearly 50,000 people fled their homes in northern Dara’a to escape bombardment, finding shelter in makeshift camps in the south of the governorate as well as in Quneitra governorate. Retaliatory shelling is also affecting the neighboring governorate of Swaida,” the U.N.’s World Food Program (WFP) notes in a statement issued Tuesday.

“We had to run during shelling and destruction to get to this camp,” a displaced man identified only as Nidal told WFP. “We’re sleeping in the open air, under the trees, in the mosques and schools. Those lucky to find a tent have to share it with four or five other families. We need all the help we can get.”

The U.K.-based Syrian Observatory for Human Rights (SOHR), which uses a network of ground sources to monitor the war, reports that the Russian-backed air assault by the Assad regime has forced up to four hospitals to shut down and killed 14 civilians, including women and children, on Wednesday alone.

Last Saturday, the Assad regime launched an air assault to recover territory in and around Daraa province from the Turkey-allied Free Syrian Army (FSA), which reportedly holds the vast majority of the area, and the Islamic State (ISIS/ISIL), among other rebel and opposition fighters.

The Agence France-Presse (AFP) agency now reports:

Syria’s army launched a ground assault on the flashpoint southern city of Deraa, state media said, after a week of deadly bombardment on the nearby countryside caused mass displacement. Government forces have set their sights on retaking the south of the country, a strategic area that borders Jordan and the Israeli-occupied Golan Heights. The escalation late Tuesday against rebels is the latest in a week-long Russian-backed campaign to retake territory lost since the start of the Syria’s war in 2011.

“The escalation in Daraa, near Jordan and the Israeli-occupied Golan Heights, came as Syria’s state media reported that two Israeli missiles struck an area near the Damascus International Airport early Tuesday, without naming a specific target,” the Associated Press (AP) adds.

Al Masdar News, a pro-Assad outlet, described the Syrian regime’s operation to retake southwest Syria as “their largest offensive of the war.”

Waseem Kiwan, a 36-year old civilian in Daraa province, told AP that Assad’s bombing campaign spared nothing.

“The area is heading toward a catastrophe, a humanitarian catastrophe in every sense of the word,” he declared. “People are living in extreme fear.”

“The safest place is the border with Israel because the regime and Russian airplanes cannot strike the area,” Kiwan added.

Although ISIS has suffered devastating losses in Iraq and Syria in recent months — losing its territorial caliphate — the jihadist group still holds shrinking pockets of land in Syria, particularly in Daraa province.