Footage has emerged which shows a tunnel network and underground hospitals left behind by militant groups in Syria’s Eastern Ghouta. It was discovered by units of the Syrian Army, according to SANA.

The video, published online by RT’s Ruptly agency, shows Syrian Army soldiers walking through the tunnel, which extends for more than 400 meters (1,312ft) and connects two underground field hospitals that were used by militants.

Following the liberation of Eastern Ghouta, the military discovered a whole network of tunnels connected to militant positions and underground bases throughout the districts of Jobar, Ayn Tarma, Arbeen, and Zamalka, according to SANA. Eastern Ghouta had been occupied since 2012.

Militants left the area after Russian-brokered agreements on daily humanitarian ceasefires and deals made between militants and Syrian government forces. Starting late February, these efforts enabled more than 150,000 civilians to finally leave the militant-controlled areas for safety. Meanwhile, jihadist groups, rebels and their families relocated out of the Eastern Ghouta area and into other rebel-held areas.