A fire has erupted at one of the Midwest's biggest greenhouse operations, spewing heavy black smoke. No injuries have been reported from the fire at Ohio's Green Circle Growers. Firefighters from several towns have been tackling the intense flames while dealing with powerful wind gusts and very cold weather at the greenhouses along a highway in Oberlin. The cause of the fire hasn't been determined. Green Circle Growers says the heat for its greenhouses comes from a wood boiler fueled by refuse from tree removal companies.