At least four people were killed and one person was injured after a Sri Lanka Air Force plane crashed near Colombo Friday, police said.The plane, with five people on board, was on its way to the Sri Lankan domestic airport in Ratmalana city when it crashed at a rubber estate in Athurugiriya after hitting the roof of a house, Xinhua reported.The Air Force Antanov 32 aircraft lost contact with the ground and went missing from radar shortly after taking off from Katunayake airport in Colombo.Residents said there was thick fog over the area where the plane crashed. The pilot had reported difficulty in locating the landing strip before the plane crashed, the Sri Lanka Air Force said.