Syrian regime forces cut off the largest town in eastern Ghouta from the rest of the rebel-held enclave near Damascus, pressing on with a 20-day assault that has left more than 1,000 civilians dead.

Government troops and allied militia launched their military campaign for eastern Ghouta on February 18 and have since overrun more than half of the area, defying global calls for a halt to the violence.

The assault has followed a divide-and-conquer strategy, eating away at rebel-held territory, and government forces successfully isolated Ghouta’s main town of Douma in a blow for the beleaguered rebels. Regime fighters cut off a road linking Douma with the town of Harasta further west and also captured the town of Misraba.

Shelling and air strikes slammed into Douma, trapping residents inside their basements for hours. Rescue workers and medics were struggling to navigate the town’s rubble-littered roads to bring wounded residents back to field clinics.

At least 20 civilians including four children were killed in Douma, in addition to 17 civilians in other battlefront towns. The deaths raised the assault’s total toll to 1,031 civilians, including 219 children. More than 4,350 have been wounded.