Original sentence: A commission appointed by the central government stated that the fire had been an accident.The commission set up by the government of Gujarat to investigate the train burning spent 6 years going over the details of the case, and concluded that the fire was arson committed by a mob of 1000-2000 people, mainly Muslims
Edited sentence: The official commission set up to investigate the train burning spent 6 years thoroughly going over the details of the case, and concluded that the fire was arson committed by a mob of 1000-2000 people, mainly Muslims