DAYTON — A fire that destroyed the clubhouse of the Outlaws Motorcycle gang Sunday night was accidental, according to an investigation by the state Fire Marshal’s Office.

The fire marshal dispatched four investigators to the scene. They determined the fire started near a propane water heater in a bathroom. The bathroom was located in a mobile home that was attached to the building, said a statement from the Fire Marshal’s Office.

Investigators working with deputies from the York County Sheriff’s Office also determined that the building was locked when firefighters arrived.

Department of Public Safety spokesman Steve McCausland said it is not unusual to assign four investigators to determine the cause of a fire.

The Outlaws have been in the news in Maine recently as members have been convicted of federal crimes stemming from an ongoing feud with the Hell’s Angels motorcycle gang and affiliated groups.