The state fire marshal's office has ordered an arson investigation of the fire at the Riviera Roadhouse in Braceville, Ill. about 65 miles south of Chicago, The Chicago Tribune reported Wednesday.
Fire crews from several towns were called to fight the blaze that erupted Tuesday night.
Water had to be trucked in because there were no fire hydrants in the area.
One fire official told the Tribune there were reports of explosions at the restaurant before the fire broke out.
Built in 1928, the Riviera Roadhouse featured a basement dining area and bar where people would dance and drink during Prohibition.
The owners say there was a vault in the restaurant where Capone and his cronies would hide booze and slot machines during a raid.