Kidnapping and killings of both foreigners and game park workers are common in the Democratic Republic of Congo.
Congolese soldiers and park rangers are searching for two British tourists kidnapped in the country's volatile eastern borderlands, an army spokesman said.
It is believed they were visiting the world-famous gorilla sanctuary the Virunga National Park when they were taken on a route after a ranger was killed in the park today. One of the park guards who accompanied the tourists was killed in the ambush, said Joel Wengamulay, the park's communications director, according to United Nations radio.
The gunmen fatally injured a female park ranger travelling with the tourists, and kidnapped the two Brits and their driver, VOA Afrique reports.
Unidentified armed men ambushed a group on Friday morning inside the Virunga National Park.
Located in Congo's North Kivu province, the park is one of the most important conservation sites in the world, covering 7,800 square kilometres (3,011 miles) - three times the size of Luxembourg.
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The British Foreign Office confirmed it was in contact with the Congolese authorities following the incident and said its staff were supporting their families.
He said the park is protected by around 800 rangers but there are also estimated to be between 1,500 and 2,000 militia in and around the park.
It was the deadliest attack in recent years and took the total number of rangers killed to 175.
The Foreign Office has issued warnings not to travel to large parts of the DRC.
It is a Unesco world heritage site and is home to critically-endangered mountain gorillas as well as lions, elephants and hippos. He said they have established that the tourists are British.