The militia seized the pivotal city of Goma, threatening a new humanitarian crisis in a region that has suffered decades of fighting.

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

Colleta Nzabonipa, 54, sits among other internally displaced people who fled from various camps following fighting between M23 rebels and the Armed Forces of the Democratic Republic of the Congo, in Goma,