Militiamen killed five park rangers and their driver on Monday in eastern Democratic Republic of Congo's Virunga National Park, one of the world's last sanctuaries for the endangered mountain gorilla, the national parks director said.
The team came under gunfire around 6 a.m. local time (0400 GMT) while traveling to a base near the Ishasha border crossing with neighboring Uganda, Cosma Wilungula told Reuters.
He said the gunmen were from one of Congo's 'Mai-Mai' militias, which first formed to resist Rwandan invasions in the late 1990s and are known for their magical beliefs.
He had no further details.
Virunga, located in Congo's troubled North Kivu province, is threatened by dozens of foreign and domestic armed groups that prey on the local population and exploit the area's rich reserves of timber, gold and other resources.
More than 150 rangers have been killed protecting the park over the last two decades.
Virunga is Africa's oldest national park and a UNESCO World Heritage site. It is home to roughly half the world's remaining 900 mountain gorillas and was the subject of an Oscar-nominated documentary film in 2014.
The dense forests near the Rwandan and Ugandan borders witnessed some of the fiercest fighting during civil wars around the turn of the century that killed millions, most from hunger and disease. It has also been troubled by periodic insurrections since then.
This story was written by Reuters.