Fighting has escalated sharply in recent weeks in eastern Congo, where rebels have seized key towns and are closing in on the city of Goma, the government’s last stronghold in the North Kivu province,

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.

Fighting with M23 rebels in eastern Congo left six United Nations peacekeepers dead, U.N. officials said Saturday.