Los Angeles Fire Department Captain, Matthew McKnight, 51, died August 12th after collapsing while on-duty at the department’s Metropolitan Fire Communications Center.

McKnight was found unresponsive at the downtown facility at 1:07 a.m. Despite an exhaustive effort by colleagues who immediately performed CPR, applied a defibrillator and instituted advanced life support measures, Captain McKnight proved beyond medical help and was declared dead Monday morning at the Los Angeles County/USC Medical Center.

Authorities say no one witnessed McKnight collapsing. He was last seen at 12:55 a.m. toward the end of a five-hour watch, supervising 11 dispatchers.

An autopsy will determine the cause of death.

McKnight was a 31-year veteran of LAFD and lived in Thousand Oaks. He leaves behind a wife, a teenage daughter, a pre-teen son and two brothers, who are both members of the LAFD.