Emergency officials confirm an electrical explosion happened around 5:30 p.m., but the cause is still under investigation.
Ameren Missouri said in a written statement that the accident occurred in the switch yard area, but a company spokesman declined to elaborate about what happened.
The St. Louis-based power company said that the incident did not affect the operations of the nuclear plant, which it said continues to function safely.
Ameren said it was not providing details about the status of the injured workers out of respect for their privacy.
Callaway County Emergency Management Director Michelle Kidwell said the 911 call reported burn victims, including two with burns to the face.
One person was flown to University Hospital in Columbia, however the extent of their injuries is still unknown.
Continue reading at Explosion at Callaway nuclear plant injures three people