Gunmen attacked the village of Mpama, a few kilometres from the Bisie cassiterite mine, in Congo’s violence-ravaged North Kivu province early on Wednesday. "The provisional death toll is 16 dead," North Kivu’s provincial mines minister Juma Balikwisha told Reuters. "Security has been reinforced. We have sent elements. Activity at the mine has not been suspended," said Dieudonne Tshishiku, an official for the Walikale district in which the mine is situated. Bisie is the largest artisanal mining site in the DRC.

Raids on mines are uncommon, with many militia groups instead extorting money along mineral transport routes. "Historically, armed groups have rarely attacked mining sites directly," said Nicholas Garrett, a Congo mining expert with London-based Resource Consulting Services. "This attack seems to be a departure from this pattern. It’s too early to say if this will lead to a long-term disruption of the trade."

U.N.-supported Radio Okapi reported that local mining police believed as many as 40 people had been killed, while a mining official said the number of injured had risen to 65 from an earlier figure of 45. Authorities say they suspect the attack was carried out by a new Mai Mai militia with links to the Rwandan Hutu rebel group the Democratic Forces for the Liberation of Rwanda (FDLR).

Congo’s army, with the backing of the world’s largest peacekeeping mission, launched operations against the FDLR this year in an effort to stamp out one of the root causes of more than a decade of violence in the east. However, the anti-rebel campaign has inflicted a heavy toll on civilians, forcing hundreds of thousands of villagers to flee their homes. The FDLR has forged alliances with a number of Mai Mai militias and carried out a series of reprisal attacks that aid agencies say have killed hundreds of civilians.