SAN DIEGO -- A mechanic for an ambulance service was sentenced Tuesday to three years in state prison for threatening the supervisors who fired him and choking his girlfriend, who worked as a dispatcher for the company.

Brandon Murray, a 27-year-old former Marine with post-traumatic stress disorder, pleaded guilty to making criminal threats, domestic violence assault and a misdemeanor count of possessing a loaded weapon in his vehicle.

He was sentenced by Superior Court Judge Michael Smyth.

Over the past year, Murray had several confrontations with his superiors at Alert Ambulance Network, and on Aug. 21, the company suspended him for two days and scheduled a meeting for the following Monday, said prosecutor Harrison Kennedy.

Over that weekend, Murray choked his live-in girlfriend and later tried to get back into the residence by pushing an air conditioning unit onto her, injuring her face, arms and legs, according to the prosecutor.

That Monday, the woman got to work before Murray and learned that company executives planned to fire him, Kennedy said.

The woman called Murray to alert him, and the defendant in turn called administrators and told them they would have to "face his arsenal," the prosecutor said.

The woman left work and called co-workers, warning them that they should leave too, because Murray was on his way, Kennedy said.

She then met up with the defendant, and police spotted the couple and made a traffic stop, finding four loaded semi-automatic weapons and 149 bullets in the trunk of Murray's car, the prosecutor said.

Defense attorney Michael Earle said Murray was an ex-Marine who had just returned from Afghanistan when he started working for the ambulance company.

Earle said Murray needs treatment for PTSD because the military cannot provide it.