The person, whose name has not been released, was shot and killed, Sheriff Rosie Rivera in Salt Lake County said at a news conference. Both deputies have been taken to hospital for treatment.
One deputy is in stable condition after being shot in the face and the other is in critical condition after being shot in the eye, she said.
The deputies were part of a campus security team in the prison when an altercation began in a grassy area near the parking lot around 10:30 a.m., Rivera told reporters.
Rivera said it was unclear what triggered the altercation. A critical incident team involved by an officer has been called to investigate the shooting, she said.
“Incidents like this are really devastating for the department. And we hope and pray that our deputies will be fine,” Rivera said.
“The law enforcement environment is extremely dangerous right now and we know it,” she added.
The South Salt Lake City Jail Complex includes the headquarters of the sheriff’s office. The prison is locked according to standard protocol, and roads in the area will be closed “for a considerable time” to the investigation, Rivera said.
“It’s terrible when someone in law enforcement is in a situation like that,” she said. “For our sheriff’s deputies and our staff, it’s something you don’t really expect to happen on a Saturday morning.”