Three inmates were in the hospital late Wednesday after a fight at the Utah State Prison's maximum-security area.
The Utah Department of Corrections didn't immediately say what sparked the fight or release the extent of injuries.
One inmate was flown to a hospital by helicopter and two were driven by ambulance, said corrections spokeswoman Maria Peterson.
The scuffle broke out sometime after 8 p.m. in the prison's Uinta facility, which houses death-row inmates and others, Peterson said. The conflict involved fewer than 10 inmates, all men. Their names have not been released.
No prison employees were injured, Peterson said.
The area was on lockdown as corrections officers began investigating what happened, Peterson said. There is no deadline on the probe, she said, but the results will be publicly released.
"Unfortunately, fights in correctional facilities are pretty routine," she said. "It's less frequent that somebody is taken by helicopter."