Two Game rangers and a soldier have been killed by rebels in Democratic Republic of Congo’s famous Virunga National Park, officials say.
Five rebels were also killed in the attack in the park, which is one of the world’s last refuges for mountain gorillas.
Some of eastern DR Congo’s numerous armed groups are based in the park, where they often poach animals.
More than 130 park rangers have been killed in the park since 1996.
According to Reuters news agency, the M23 rebel group which has bases in the park, recently allowed tourist visits to resume.
This year’s rebellion by the M23 has caused some 500,000 people to flee their homes.
Park director Emmanuel de Merode said the rangers, who were travelling with an armed escort were ambushed by members of the Mai Mai militia.
“They came under attack from a quite substantial Mai Mai unit… It was very heavy fire received,” he told Reuters.
In July, armed groups fighting in the area agreed to let a search for mountain gorillas to proceed.
Virunga is home to 480 of the world’s 790 remaining mountain gorillas. It is one of the most bio-diverse places on Earth and is on the UN list of World Heritage sites in danger.
The mountain gorillas have been threatened with extinction because of expanding human settlements, the long-running conflict in the region, and possible oil exploration in the park.