(CNN) -- Fighting between the national army and rebels in the eastern Democratic Republic of Congo is threatening mountain gorillas, a critically endangered species, the Virunga National Park said Sunday.
Just two of the park's five gorilla patrol posts remain open after the fighting intensified and rebels reportedly moved into the area.
Virunga National Park, Africa's oldest national park, is home to roughly 25% of the world's mountain gorillas.
"We are deeply concerned with the safety of the mountain gorillas who are exposed to the dangers of artillery fire, but we must also take care of our staff who have to be evacuated from the combat zone. As soon as there is a lull in the fighting, we will return to check on the gorillas," Emmanuel de Merode, chief warden for Virunga National Park, said in a statement.
Tourist attractions will remain closed until the security situation improves, the park said.
Mountain gorillas are critically endangered with fewer than 800 left in the wild in the mountains of the Democratic Republic of Congo, Rwanda and Uganda. Some 200 are thought to live in the Virunga National Park.
Despite its rich resources, Congo battles violence and poverty. A decade of conflict between government forces and armed militias left millions dead as a result of the fighting and as a result of hunger and diseases.
The east remains the epicenter of attacks by anti-government militias. The international community has spent massive amounts of money in an effort to stabilize the vast nation.
The world's largest mountain gorilla population, thought to number fewer than 500 animals, is found in a mountainous region known as the Virungas, incorporating Uganda's Mgahinga Gorilla National Park, and Virunga National Park. A second, smaller population can be found in the Bwindi Impenetrable National Park, in another region of Uganda.
Mountain gorillas are not frequently hunted for their meat, but can be maimed or killed by poachers leaving traps or snares for other animals. They have also been killed for their body parts to be sold to collectors.