April 9 (UPI) -- Five rangers and a driver were killed in an ambush in the Democratic Republic of the Congo's Virunga National Park on Monday.
A sixth ranger was injured in the attack, which took place in the central sector of the park.
"Virunga National Park is deeply saddened to confirm reports of an attack on our staff today," the park said via its Twitter account.
The attack was the worst loss of life in the park's history, according to the Guardian.
Virunga National Park has seen more than 170 rangers get killed over the past 20 years as anti-government rebel groups, local bandits and rare animal hunters roam the area.
Last week, a ranger was killed when armed men attacked a construction site for a hydroplant.
In an interview with National Geographic last year, Virunga National Park Director Emmanuel de Merode said three main groups are responsible for the violence in the park.
"The Allied Democratic Forces and National Army for Liberation of Uganda operate together in the north. They are an extremist Islamic movement operating to undermine the government of Uganda," de Merode said. "Then the Mai-Mai, who are Congolese, operate in the center of the park. In the south is the Democratic Forces for Liberation of Rwanda, many of whom were responsible for the 1994 genocide in Rwanda."
"The hardest part of my job is having to bury the men that have been entrusted to me," he added.
In 2014, Netflix released Virunga, a documentary on the Virunga park rangers who are tasked with protecting the critically endangered mountain gorilla.
The Virunga Mountains are one of only two places in the world where the mountain gorilla is found. The other location is the Bwindi Impenetrable National Park in Uganda