At least 12 rangers have been killed by suspected members of a Rwandan rebel group in the Virunga National Park in the Democratic Republic of Congo.
Government official Cosma Wilungula said Friday’s attack was the deadliest in recent history.
He said about 60 militiamen had ambushed a convoy of civilians that was being protected by the rangers.
Africa’s oldest nature reserve is a popular tourist attraction, known for its population of mountain gorillas.
The biologically diverse park is a Unesco World Heritage site in the restive east of the DR Congo.
Another six people were injured in the attack blamed on militiamen from the Democratic Forces for the Liberation of Rwanda (FDLR), whose leaders have been accused of links to the 1994 genocide in which some 800,000 ethnic Tutsis and moderate Hutus were killed.
The group has so far made no public comments on the accusations against it.