A spokesman for the U.N. mission in Congo says four missing U.N. peacekeepers have been found following an attack that left two others dead.

Felix Prosper Basse told The Associated Press on Wednesday that the four Tanzanian peacekeepers who went missing during the attack have been located.

Basse said it still wasn't clear which of the many armed groups in eastern Congo was responsible for the killings, though others have said that members of a Ugandan rebel group may have carried out the attack.

The ambush came a day after gunfire hit a helicopter carrying the mission's force commander in the same region.

Mineral-rich eastern Congo has been plagued by a number of armed rebel groups since the Rwandan genocide two decades ago.