Their vehicle was ambushed while bringing the tourists from Kibumba to the city of Goma, Joel Wengamulay, spokesman for the Congolese Institute for The Conservation of Nature, told the United Nations -backed Radio Okapi.
Two British citizens have been kidnapped in the Democratic Republic of the Congo, the Foreign Office has confirmed.
A spokesperson for the Congolese Institute for Nature Conservation (ICCN) said: "For the moment the [ICCN] can not communicate much about the incident because the hostages are still in captivity".
Mai-Mai militia were blamed for an attack in which five rangers and a driver were killed in an ambush in the park.
Unidentified armed men ambushed the group on Friday morning north of Goma, the capital of Democratic Republic of Congo's North Kivu province, inside Virunga National Park.
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In the Virunga National Park in the Democratic Republic of the Congo, unknown gunmen killed one of the guards of the Park and kidnapped the two tourists from the United Kingdom and their driver.
In an interview with National Geographic a year ago, Virunga National Park Director Emmanuel de Merode said three main groups are responsible for the violence in the park.
It is a Unesco world heritage site and is home to critically-endangered mountain gorillas as well as lions, elephants and hippos.
More than 175 rangers have died protecting Virunga National Park, which is located in the rugged mountains and volcanic plains adjacent to neighbouring Rwanda and Uganda.
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".