U.N. peacekeepers in the troubled region have used aircraft to monitor the flow of the lava, aiding rangers on the ground who help protect the local endangered apes and chimpanzees.
According to officials at Virunga National Park, the eruption has been “very destructive” to the chimpanzee range on the western slope of the vast volcano.
The eruption began before dawn on Saturday, with molten rock raining down on the forest slopes of the mountain.
“I was awoken at 3.45 a.m. by a loud bang, which I at first thought was the sound of war,” said Innocent Mburanumwe, the warden for the southern Mikeno Sector of Virunga.
Lava has since flowed for miles down the flanks of the volcano, causing a long, eerie red glow that can be seen for miles.
Nyamulagira is believed to be about the most active volcano in the world. It erupts about every three to four years, with a 2006 blast blanketing large areas of surrounding forest with volcanic rocks.
An eruption in 2002 covered the region’s largest city of Goma with lava.
Virunga National Park is a UNESCO World Heritage Site. It is home to around 200 of the world's last 750 mountain gorillas.
But those primates are mainly located well east of the volcano, near the border with Rwanda.
Photo: Virunga National Park (DR Congo)