An aircraft carrying 15 humanitarian aid workers and two crew members has crashed into a steep ridge near Bukavu in the eastern Democratic Republic of Congo, apparently killing everyone on board.

An aerial survey of the crash site early on Tuesday indicated there were no survivors, the organization which contracted the flight said in a statement.

The aircraft was approaching Bukavu on a flight from Kisangani on Monday when it disappeared in bad weather. “The last known radio contact was made 10 minutes inbound to Bukavu in heavy rain,” Air Serv International said in an earlier statement.

The Associated Press reported on Tuesday that Elisabeth Byrs of the United Nations Office for the Coordination of Humanitarian Affairs said in Geneva that rescuers were at the scene.

The identities of the passengers and crew were not disclosed, but the AP quoted a spokesperson for a South African aircraft leasing company, CemAir, as saying that its crew were piloting the aircraft. The company operates Beech Airliners which carry up to 19 passengers.

Air Serv International, which contracted CemAir to run the service, describes itself as a not-for-profit aviation organization that supports humanitarian programmes.