When the blaze was extinguished, firefighters found a body inside.
They aware unable to establish the identity of the person or the cause of the fire.
A crime scene has been set up, and investigations into the fire have started. The Homicide Squad from the State Crime Command has been notified about the situation.
Bells Line of Road is still closed in both directions between Mt Tomah Road at Mount St and Darling Causeway at Bell.
Motorists are being told to avoid the are and use the Great Western Highway and Darling Causeway instead.
Investigators are appealing to anyone with information to come forward or to contact Crime Stoppers.
They are also seeking anyone with dashcam footage recorded in the area between 10am-10:45am this morning to inform police.
