INDIANAPOLIS (AP) — Nearly a dozen inmates were injured in falls or fights after a power outage plunged a privately operated jail in Indianapolis into darkness early Monday and a backup generator failed to kick on, officials said.

Crews with Indianapolis Power & Light had reportedly disconnected a power line in the area that had an ice accumulation when the outage hit Marion County Jail II just after 3:30 a.m., Marion County Sheriff Kerry Forestal said.

But the utility said in a statement that its crews were not working in the area before the outage. Instead, the utility said its crews responded to an emergency call from the sheriff’s office about the power loss after “frozen water on a conduit pulled wires on an IPL pole and caused the outage.”

As the crews were making repairs “the jail’s backup generator initially failed causing it to turn on and off several times, which interrupted power at the jail,” utility spokeswoman Brandi Davis-Handy said in a statement, adding that the jail’s power was restored about 4:30 a.m.

Eight inmates were sent to a hospital after suffering broken bones or minor injuries in either in falls or fights that broke out among inmates in the darkness, Forestal said. Three other inmates were treated at the jail for lesser injuries, and no inmates were critically injured.

At the time of the power outage, Forestal said 1,226 inmates were inside the jail, which is on the eastern edge of downtown Indianapolis. The jail is run by CoreCivic, which has a contract to house up to 1,233 inmates — all men.

The jail’s power was out for a total of about 10 minutes between about 3:30 a.m. and about 4:10 a.m. as the power repeatedly came on and off, said Katie Carlson, a public information officer for the Marion County Sheriff’s Department.

Forestal said the jail’s generator is checked weekly.

Unlike the Marion County Jail, which is in the middle of downtown Indianapolis and run by the sheriff’s office, the Marion County Jail II does not house women or juveniles, she said.