China confirmed Thursday that an armed attack in the Democratic Republic of Congo left several of its citizens dead or missing.

Local sources told AFP on Wednesday that a militia attack on a mining site in gold-rich Ituri province killed at least four Chinese nationals.

China’s foreign ministry said a private Chinese company in the DRC “was attacked by armed forces, resulting in the death and disappearance of several Chinese nationals,” without specifying the number.

“China expresses its strong condemnation of this attack,” ministry spokesperson Mao Ning said at a regular press conference.

“We demand that the DRC side hunts down the killers as quickly as possible and strictly punishes them in accordance with the law,” she added.