Several firefighters were being treated at a hospital after battling a blaze at a Central Falls mill building that started by a paint-mixing process. Central Falls Fire Chief Robert Bradley told WPRO-AM that the fire started Monday with a mixing process that used at least one highly toxic chemical. Firefighters from more than a dozen communities responded. Medical crews from Memorial Hospital were on the scene as a precaution. Several firefighters were taken to the hospital for heat exhaustion. It was not immediately clear whether they had been exposed to chemicals. Bradley told the station that some of the gear used to fight the fire must be discarded because of exposure to the chemical.