A humanitarian aid flight carrying 17 people crashed on a ridge in eastern Congo, and the U.S.-based group that operated the route said Tuesday there appeared to be no survivors.

The 21-seat Beechcraft 1900 aircraft went missing in bad weather late Monday with two crew and 15 passengers on board, a spokeswoman for the U.N. Office for the Coordination of Humanitarian Affairs said.

It was found Tuesday morning, 9.4 miles (15 kilometers) northwest of the airstrip at Bukavu in eastern Congo, its intended destination, Elisabeth Byrs told journalists in Geneva.

U.S.-based Air Serv International, which runs the twice-weekly aid delivery between Kisangani and Bukavu, said in a statement that the plane was on a steep ridge and that helicopter surveys suggested all 17 aboard had died.

"According to the information in our possession, there were no survivors," Amy Cathey, a manager for Air Serv in the regional capital, Goma, told Congo's U.N.-funded radio station.

The U.N. teams were "securing the site and searching for and recovering victims' bodies," Cathey said.

The U.N.'s Byrs said she had no confirmation of casualties. The identity of the passengers and crew was not immediately disclosed.

Air Serv International, based in Warrenton, Virginia, describes itself as a not-for-profit aviation organization that supports humanitarian programs worldwide.

No Air Serv personnel were involved in the crash, spokeswoman Suzanne Musgrave told The Associated Press by telephone from Warrenton.

She said the plane was being flown by a South African commercial company, Cem Air.

A senior official with Cem Air confirmed that it owned the plane used for the flight and that two of its crew were flying the aircraft.

"I'm in contact with the South African air force base there, and they haven't given me any information about any survivors or whether we know it was our airplane," Cem Air's chief pilot MJ Booysen said by telephone from South Africa.

"The airplane at this point is missing, but we are on standby for further information," he said.