Goma, Congo — Residents in eastern Congo’s largest city, Goma, were fleeing on Monday after Rwanda-backed rebels claimed to have captured the regional hub from Congolese forces as fighting escalated despite calls from the U.N. Security Council for the insurgents to withdraw.

Residents of Goma reported gunfire and shelling after rebels overran Congolese troops. U.N. officials estimated that more than 1 million displaced people were now inside the city.

The M23 militia, funded and directed by Rwanda, said it had seized the city of Goma, terrifying its people, many of whom sought shelter there after fleeing the rebel advance.