HARRIMAN, Tenn. — A retention pond wall collapsed early this morning at a power plant run by the nation's largest public utility, releasing a frigid mix of water and ash that flooded as many as 10 homes and put hundreds of acres of rural land under water.

The 40-acre pond was used by the Tennessee Valley Authority to hold a slurry of ash generated by the coal-burning Kingston Steam Plant in Harriman, about 50 miles west of Knoxville, said TVA spokesman Gil Francis. An earthen wall gave way just before 1 a.m., flooding the road and railroad tracks leading to the plant, which is in a mostly rural area.

Authorities said no one was seriously injured or needed to be taken to the hospital.

Emergency workers helped people out of two partially collapsed homes and used four-wheel drive vehicles to check other homes where people couldn't drive out, said Roane County Rescue Squad spokesman Brian Grief.

Howie Rose, the director of the Roane County Office of Emergency Management and Homeland Security, said a train carrying coal to the plant reached the point on the tracks that is flooded and couldn't go forward or back up. He said there were no injuries and authorities were trying to assist the train.