Critical minerals factor into the fight.

Residents of the besieged city of Goma, in the east of the Democratic Republic of Congo, say they are gripped by fear as gunshots continue to ring out around their homes, days after rebel forces claimed they had taken over.

The scene is the result of the invasion of Goma on January 27th by M23, an armed group under the control of Rwanda, Congo’s neighbour, which abuts the city. Paul Kagame, Rwanda’s president, has escalated a crisis whose origins go back decades.

Rwanda-backed rebels claimed they captured eastern Congo’s strategic city of Goma, the hub of a region containing trillions of dollars in mineral wealth that remains largely untapped, the Associated Press reported.

Bodies are lying on the streets. Medical staff in overwhelmed hospitals are treating hundreds of wounded civilians against the backdrop of gunfire and mortar fire.

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

The mineral-rich east of the Democratic Republic of Congo has been dogged by conflict for more than 30 years, since the 1994 Rwandan genocide.Numerous armed groups have competed with the central authorities for power and control of the potential fortune in this vast nation.

M23 rebels captured the key city of Goma in the eastern DRC Monday, forcing thousands of civilians to flee in the latest in a series of advances - Anadolu Ajansı

U.S. Secretary of State Marco Rubio called for a urgent cease-fire in the conflict in eastern Democratic Republic of Congo saying Washington was "deeply troubled" by a recent escalation in the fighting.

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.

GOMA, Democratic Republic of Congo (Reuters) -Congolese rebels said on Sunday they had taken Goma, the biggest city in the east of the mineral-rich country, after a lightning advance that has forced thousands of people to flee and fuelled concerns of a regional war.