All 54 people on board a Trigana Air aircraft were killed in a crash two days ago in Indonesia ' s Papua province, the latest in a string of aviation disasters in the Southeast Asian archipelago, research team announced on Tuesday. Major-General Heronimus Guru, operations director at Indonesia's National Search and Rescue Agency, told a news conference in the capital that the passengers' remains were being put into body bags and recovered. Officials have declined to comment on the cause of Sunday's crash until the results of an investigation by the national transport safety committee, but Guru said the terrain in Indonesia's easternmost province may have been a factor. "There's a possibility the aircraft hit a peak and then fell into a ravine because the place that it was found is steep," he said. Treacherous terrain of forest-covered ridges hampered rescuers' efforts to reach the site where the Trigana Air Service ATR 42-300 plane came down. The aircraft's black box flight recorder, which should provide investigators with some answers, was found in the early afternoon, Transport Ministry spokesman Julius Arivada Barata told Reuters by text message. There were 44 adult passengers, five children and infants and five crew, on the short-haul flight from provincial capital Jayapura south to Oksibil town.