Rwandan-backed M23 rebels appeared on Friday to be closing in on eastern Democratic Republic of Congo's second-largest city, Bukavu, as they seized control of the nearby airport of Kavumu, prompting Congolese troops to withdraw in some areas.

Families remained indoors and shops remained closed as M23 fighters entered the outskirts of Bukavu — a city of about 1.3 million people that lies 63 miles (101 kilometers) south of Goma, the region's largest city taken by the rebels last month.

The Democratic Republic of Congo has been mired in conflict for years. As fresh fighting surges in the east, the roots of today’s violence can be traced back to old problems.