Assailants killed three rangers and another member of their convoy in an ambush in eastern Democratic Republic of the Congo on Thursday morning, the Congo Institute for Nature Conservation (ICCN) said.
The attackers struck as the convoy, escorted by ICCN rangers, left Kivandya village near Virunga National Park, which is home to half the global population of endangered mountain gorillas and the scene of frequent militia attacks.
The fourth victim was one of the technical workers traveling in the convoy who were implementing a project to support communities around Virunga, ICCN said in a statement.
An additional six people were wounded, it said.
Virunga has been caught in the middle of militia activity that has destabilized surrounding South Kivu province since civil wars fought around the turn of the century.
The ICCN warned of a resurgence of violence in February after suspected Mai Mai militants attacked a ranger position in Virunga, killing one and injuring two.