M23 rebels in the Democratic Republic of Congo have captured the eastern city of Bukavu with the backing of Rwandan forces, the second major city in the mineral-rich Kivu region to fall in three weeks.

Rwanda-backed rebels have reached the center of east Congo’s second-largest city, Bukavu, and taken control of the South Kivu province administrative office.

Rebel forces have been seen in the center of Bukavu, the second largest city in the eastern Democratic Republic of Congo (DRC), on Sunday, residents told CNN, as the fighters push to expand their foothold in the mineral-rich region.