Rwanda-backed rebels entered the outskirts of eastern Congo’s largest city, Goma, on Sunday, causing what the United Nations called “mass panic” among its 2 million people and leading Congo’s government to call it a “declaration of war.

Rwanda has been urged to withdraw its advancing troops from the outskirts of Goma, a mineral-rich city in the Democratic Republic of Congo (DRC).

Rebels in Democratic Republic of Congo are closing in on a key city in the mineral-rich region aided by neighboring Rwanda’s army, the head of a peacekeeping mission told United Nations Security Council members during an emergency meeting on Sunday.