UPDATED 1:30 p.m. with new details on injuries, explosion.

MADISON • Three people were being treated for injuries after a flash fire at an ethanol plant in Madison, authorities siad.

The plant, run by Abengoa Bioenergy of Illinois, is near Route 3 in the 300 block of Bissell Avenue, a fire official said. It is the site of the old Army depot.

The report of an explosion came out at about 9 a.m., according to Madison Fire Chief Jeff Bridick. Men were working near a container in a maintenance shed when the container exploded.

The fire had burned itself out by the time firefighters arrived, Bridick said.

The three injured workers included one with serious burns to the lower extremities. He was taken to St. John's Mercy Medical Center. The others received more minor burns to the head and neck. They were taken to a hospital in Illinois. Bridick declined to give their names.

No one from the plant or at Abengoa's corporate office in Chesterfield was available for comment.

Bridick declined to give more details about the explosion pending an investigation by the Occupational Safety and Health Administration.

"Right now the cause of the fire and explosion is under investigation," he said.