Congolese rebels and allied Rwandan troops claimed on Monday to have captured the mineral-rich city of Goma, as thousands fled fighting that killed at least 13 peacekeepers over the weekend.

M23 rebels in the Democratic Republic of Congo were reported to have taken the key eastern city of Goma in fierce fighting with government forces that sent streams of refugees fleeing area communities.

Residents of eastern Congo's largest city of Goma greeted the arrival of Rwanda-backed rebels with trepidation on Monday, some staying indoors and others coming out to cheer in what one called a "show" of happiness.

In the last 48 hours, two U.N. peacekeepers from South Africa and one from Uruguay were killed and 11 peacekeepers were injured and hospitalized.

M23 rebels marched into east Congo's largest city Goma on Monday and Congolese troops exchanged fire with the Rwandan military across the border, in the worst escalation of a long-running conflict for more than a decade.

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.