Seven people were killed when a Nigerian Air Force (NAF) Dornier-228 aircraft crashed into a house at a military cantonment in Kaduna state on Saturday.The aircraft was bound for capital Abuja and had taken off from the Kaduna military airfield, an air force official told Xinhua news agency reported.The seven people were the pilot, co-pilot, two engineers and three passengers. All bodies have been recovered.However, the cause of the crash remains unknown.