Rescuers had to dig for hours to free one of the workers from the rubble at the Killen Generating Station, Adams County Sheriff Kim Rogers said. Rogers said that worker was conscious.
It was not clear what caused the collapse.
"Next week, they were preparing to take that building down and those stacks. So this was some kind of preparation to take that building down,” the sheriff said.
There was no word on the condition of the injured and authorities have not released any names.
Rescue crews remained on the scene.
The coal-fired generating station opened in 1982 and was closed in May 2018.
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