WILKES-BARRE, Pa. (AP) — A correctional officer and an inmate died following a brief altercation at a Pennsylvania prison, officials said.

It happened Monday evening at the Luzerne County Correctional Facility in Wilkes-Barre, according to Luzerne County Manager David Pedri.

The Times Leader reported that Pedri confirmed the deaths at a news conference late Monday, calling the incident "sad and tragic." He declined to comment on what led to the altercation or how the two died, citing the ongoing investigation.

Officials identified the inmate as Timothy D. Gilliam Jr., 27, who was behind bars for failing to register as a sex offender. Officials did not release the name of the correctional officer, at the request of the officer's family.

"This guard went to work today believing that he would be coming home," Pedri said. "And sadly that didn't happen."

The prison went on lockdown after the incident, which Pedri described as isolated.

"We will do everything in our power to ensure an incident like this never happens again," Pedri said.

Monday was the first day on the job for the new correctional services division head, Mark Rockovich, who Pedri said spoke to the other correctional officers about what happened.

The Luzerne County District Attorney's Office and Pennsylvania State Police are investigating the incident.