An explosion at a coal-burning power plant killed one person and injured up to a dozen others Monday, utility officials said.

The blast killed a delivery driver who was unloading hydrogen, used as a coolant for steam generators at the Muskingum River Plant, but it wasn't immediately clear what exploded, said Melissa McHenry, a spokeswoman for American Electric Power, based in Columbus.

There was no major damage to the southeastern Ohio plant, said Washington County Sheriff Larry Mincks. About 200 people work there.

Hydrogen gas, while highly explosive, is used at the plant because it has a high capacity for heat and is more efficient than using air to cool generators.

McHenry said AEP officials reported six to eight people were hurt, most with minor injuries. Mincks said 10 to 12 people were taken to hospitals. None of the injuries was considered life-threatening, the sheriff's office said.

At least six people were sent to hospitals in nearby Marietta and Parkersburg, W.Va., hospital officials said.

AEP is one of the nation's largest power generators, with more than 5 million customers in 11 states.