Two British citizens have been kidnapped in the Democratic Republic of Congo, sources have said.
On its website, it has advised against "all but essential travel" to some Eastern cities amid an increase in reports of attacks by armed groups as well as military and police stop-and-search checkpoints.
The Britons were among a group of people taken hostage, according to a spokesperson for the Congolese Institute for Nature Conservation (ICCN). "That would put their lives in danger".
Local media reports say the ranger shot dead was female and acting as a guard, while the United Kingdom citizens were taken along with their Congolese driver.
Last year, a fifth of the park's southern sector was deforested owing to illegal charcoal production.
The rising death toll has earned the park, which is a Unesco world heritage site, a reputation as one of the most unsafe conservation projects on the planet.
Virunga is home to about one-quarter of the world's remaining mountain gorillas.
Political instability in the Democratic Republic of the Congo had caused rising violence in the province of North Kivu, where the park, famous for its mountain gorillas population, is located.
In April, the director of Virunga National Park, Emmanuel de Merode, told the BBC World Service that recent attacks were part of "a bigger picture which involves the trafficking of natural resources".
A number of kidnappings have taken place in the park in the past six weeks.
Five rangers and a driver were killed on 9 April.
A bullet riddled signal marks the doorway to Virunga Nationwide Park, occupied by rebels and different armed militias throughout years of battle close to Goma in japanese Congo.