As an East African bloc urged an immediate ceasefire in eastern Democratic Republic of Congo, Rwandan-backed M23 rebels who seized the city of Goma extended their advance on Wednesday, and Congo said it planned a campaign to recover lost territory.

Much of the beleagured city of Goma was calm early Wednesday morning, after a day during which thousands of fleeing people hunkered down by roadsides as missiles flew and injured people streamed to overwhelmed hospitals.

Rwanda-backed rebels claim they have captured eastern Congo’s largest city, Goma, as the United Nations describe a “mass panic” among its 2 million people and Congo’s government say the rebel advance was a “declaration of war.