KINSHASA (Reuters) – Armed men attacked a group of journalists and park rangers in a remote east Congo wildlife reserve overnight into Saturday, and an American journalist and three guards were missing, a local official said.

The group attacked comprised the American and two Dutch journalists and 13 Congolese park rangers. They were near the town of Mambasa in Okapi Wildlife Reserve, Mambasa territory administrator Alfred Bongwalanga told Reuters by telephone.

The two Dutch journalists and all but three of the rangers had been found and were safe. Bongwalanga did not know which of the several armed groups roaming eastern Congo was responsible.

Kidnapping of locals and Westerners for ransom has been on the rise in eastern Democratic Republic of Congo, a tinderbox of rebel groups and militias left over from a 1998-2003 war.

But Bongwalanga said there was no evidence the journalist or guards had been kidnapped.

“I can’t confirm any hypothesis that this was a kidnapping … That does sometimes happen in Ituri (province where the reserve lies) but it has been more than a year since the last one,” he told Reuters by telephone.

“The army has deployed. Search and rescue efforts are underway but this is a dense forest,” he added. “We remain optimistic that we will find them.”

In May armed bandits killed a Congolese park ranger and briefly kidnapped two conservation workers, including a Frenchman, during an ambush on South Kivu’s Itombwe Reserve.

Park rangers in east Congo trying to protect dwindling populations of elephants and gorillas often clash with poachers and other armed criminals who exploit the area’s minerals, wildlife and other resources.