MARION, Ind. — Authorities say six firefighters have suffered minor injuries after two explosions and a fire at the former Thompson Consumer Electronics plant in Marion.

Marion Fire Chief Geoff Williams says two tanks containing unconfirmed substances exploded, causing ringing in the ears of four firefighters, and another firefighter cut his hand. Assistant Chief Tony Fox says a sixth firefighter injured his shoulder in the Saturday evening blaze.

Five additional fire departments were called in to assist with extinguishing the fire.

The cause of the fire is under investigation.

The plant also was the scene of a 2004 fire hours after Thomson announced the plant’s sudden closing. One of the nearly 1,000 workers who were laid off later was charged with arson.