Veteran corrections officer Andrew Lansing was fatally assaulted by an inmate on Christmas Day at Ohio’s Ross Correctional Institution.

The unidentified inmate has been transferred to a maximum-security prison, and the facility is now on lockdown as authorities investigate.

Lansing, described as a respected and professional officer, was attacked under unclear circumstances and later died at a hospital.

The prison, operating with staff shortages and a high percentage of inmates identified as security threats, had previously reported decreased violence against staff but rising inmate fights, ABC News has reported.

Officials called Lansing’s death a heartbreaking tragedy.

Written by B.C. Begley