Rwandan-backed 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.

M23 rebels claim they now control the Congolese city of Goma—an act Congo's government described as a 'declaration of war.'

The M23 militia, funded and directed by Rwanda, said it had seized the city of Goma, terrifying its people, many of whom sought shelter there after fleeing the rebel advance.