Top UN ambassadors were forced to hitch a bus ride from Democratic Republic of Congo to Rwanda Sunday after a security guard accidentally shot a hole in their plane. The Security Council ambassadors had been visiting violent eastern Congo during a trip to promote peacekeeping operations and other efforts to end some of the most intractable conflicts in Africa. “They were boarding the aircraft to come back to Kinshasa. UN security have to surrender their weapons on the plane. He (a guard) was doing a safety check and there was an accidental discharge,” said Kemal Saiki, spokesman for the UN peacekeeping mission in Congo, the world body's biggest. “The crew thought that something may have been damaged so they decided not to fly,” Saiki said, speaking in Goma, Congo. The head of the UN mission in Congo, Alan Doss, told reporters that an investigation would be undertaken. Other eyewitnesses at the scene said the bullet, which made a loud bang inside the aircraft, went through the floor of the plane and touched a cable. The envoys and journalists accompanying them traveled by bus across the border to Rwanda, where their plane was to pick them up, Saiki said. After a four-hour bus ride through the mountainous terrain of Rwanda, the delegation was stuck for hours at the Kigali airport after US aviation fuel firm Caltex demanded $20,000 up front for fuel from the group.