The gunman who killed a security guard at a New Hampshire psychiatric hospital Friday before he was fatally shot by a state trooper was identified as a transient who had spent time living in the area, authorities said Saturday.

John Madore, 33, allegedly used a 9 mm handgun when he fatally shot Bradley Haas in the lobby of the New Hampshire Hospital in Concord, New Hampshire Attorney General John Formella announced at a news conference.

Haas, of Franklin, New Hampshire, was working security when Madore shot him. Haas, a former chief of police with the Franklin Police Department, also was an Army veteran who served for three years, Formella said.

“Chief Haas was already a hero when he walked into work yesterday, given his service to our country, to our state … he will now be remembered forever as a man who died protecting patients, staff and visitors at New Hampshire Hospital,” he said.

The violence occurred about 3:30 p.m. at the state-run hospital. After the security guard was shot, a state trooper assigned to the hospital, fatally shot the gunman, according to New Hampshire State Police.

Authorities on Saturday declined to identify the trooper who killed the suspect because the trooper has not been formally interviewed, which is agency protocol. But the trooper’s actions were lauded Saturday by Formella.

“All indications are that the actions of this trooper saved a lot of lives and that this trooper’s actions were heroic,” Formella said.

New Hampshire State Police Col. Mark Hall, who spoke at Saturday’s media briefing, said the investigation into the shooting, including the suspect’s motives, remained ongoing.

After the shooting, authorities said a state police bomb squad robot investigated a suspicious vehicle on the hospital’s campus, a U-Haul. The U-Haul was deemed not to pose a threat to the public, but inside the vehicle, investigators found an AR-style rifle, a tactical vest and several magazines of ammunition, Hall said.

New Hampshire Hospital is described on its website as the state’s premier, acute psychiatric hospital, which provides inpatient services.