The three-year insurgency by the Rwanda-backed rebel group M23 has intensified, and the U.N. warned the violence could spill into a wider war.

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.

Rwanda-backed M23 rebels claim to have captured Goma, escalating tensions in eastern Congo's mineral-rich region. UN reports mass panic as Congolese forces are urged to surrender. Congo severed ties with Rwanda,