"We are in close contact with the authorities in Democratic Republic of the Congo following an incident involving two British nationals, and our staff are providing support to their families," a spokesperson for the Foreign Office said.
The park has experienced an increase in violence in recent months.
Armed groups have staged a series of raids to steal resources, particularly charcoal.
Last month, five young rangers and a driver in the park were killed in an ambush.
Virunga is a Unesco world heritage site.
It covers 3,000 square miles on the country's border with Uganda and Rwanda.
Founded in 1925, it is home to around a quarter of the world's critically endangered mountain gorillas.
SKY News.