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.

Congolese M23 rebels entered the centre of the eastern city of Goma on Monday, two witnesses said, hours after they claimed to have seized the city despite the United Nations Security Council demanding an end to the offensive.

Fighting with M23 rebels in eastern Democratic Republic of Congo left six United Nations peacekeepers dead, UN officials said Saturday.