An attack on civilians at Virunga National Park in the Democratic Republic of Congo killed at least 18 people, including 12 rangers.
The rangers were killed "while coming to help a civilian vehicle which had come under fire by the assailants," the park management said in a statement. "Others were injured, including some who are fighting for their lives."
Virunga is a UNESCO World Heritage site with an area about 7,800 square kilometers over the borders of DRC, Rwanda and Uganda.
It is Africa's oldest and most biologically diverse protected habitat.
The park with a large population of famous mountain gorillas has been a scene of rising instability and violence for at least two decades.
At least 176 of its rangers have been killed in the last 20 years in attacks by rebel groups, militias and poachers.
There has been no claim of responsibility by any person or group for Friday’s attack.