A retention pond wall collapsed early Monday 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 located 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.

Officials originally said 15 homes were flooded, but Grief said the number is about 8 to 10.

He said rescue workers had begun evacuating a subdivision of about five houses.

“We’re going door to door and telling them it could be a couple of days before their utilities are restored,” said Grief, adding that there are broken gas and water lines in the area.

He said those forced out of their homes were being offered shelter at Roane County Community College, although there were no immediate takers.

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.

Crews were working to clear debris in the neighborhood on Swan Pond Circle Road, Rose said.

TVA experts went up in a helicopter after sunrise to assess the damage from the air. The broken dike left about 4 to 5 feet of water over 250 to 400 acres, Francis said. The Environmental Protection Agency has been notified.

The pond is used for dumping a slurry of waste from burning coal at the steam plant, Francis said. TVA will check for signs of problems at its 10 other coal-fired plants, most of which were built in the 1950s.

“They’re going to look at that for sure, but we have not had one of these (breaks) like this anywhere,” Francis said.

Investigators are still trying to determine exactly what caused the flood, but the TVA spokesman said heavy rains and freezing temperatures may be to blame. The National Weather Service reported it was only 14 degrees just before 6 a.m. in Harriman.

According to Francis, the area usually receives about 2.8 inches of rain in December. There’s been about 4.9 inches of rain so far this month, Francis said.

Knoxville-based TVA supplies electricity to 8.8 million consumers in Tennessee, Mississippi, Alabama, Kentucky, Georgia, North Carolina and Virginia.