The bucket of a track hoe pinned the worker’s leg against a slab of concrete.
The accident happened at the water treatment facility in Moore.
Police said the force crushed his leg.
Sgt. Jeremy Lewis said investigators spoke with the operator of the track hoe.
"He just says it was an accident, that his jacket or something got caught on one of the controls caused it to turn and smashed the guy," Sgt. Lewis said.
The victim works for Wynn Construction.
Police have not released his name.