CONCORD, N.H. — Investigators in New Hampshire were probing for answers Sunday as to why a man shot a security guard to death at a New Hampshire psychiatric hospital moments before being killed by a state police trooper.

New Hampshire Attorney General John Formella said Saturday that 33-year-old John Madore entered New Hampshire Hospital on Friday afternoon and killed Bradley Haas, a state Department of Safety security officer who was working at the front lobby entrance of the facility.

Michael Garrity, a spokesperson for the attorney general’s office, said Sunday that the investigation into the shooting “is active and ongoing.”

Autopsies determined that the cause of death for both Haas and Madore was multiple gunshot wounds, according to Formella’s office.

In 2016, Madore faced assault charges that were later dismissed, according to a court summary of the case. The summary, without elaborating, indicates that a judge had ordered Madore to be transported from New Hampshire Hospital for a court hearing.

Madore was most recently living in a hotel in the Seacoast region and also had lived in Concord, according to Formella. He was wielding a 9mm pistol and had additional ammunition on him when he shot Haas, who was unarmed.

Police also found an AR-style rifle, a tactical vest and several ammunition magazines in a U-Haul truck in the hospital’s parking lot and were investigating connections between the truck and Madore.

The shooting happened around 3:30 p.m. and was contained to the front lobby of the 185-bed facility, according to investigators. CPR was performed on Haas, who later died at Concord Hospital.

On the day of the shooting, there were 152 patient beds occupied at the hospital according to a daily patient census report by the New Hampshire Department of Health and Human Services. The facility is the only state-run psychiatric hospital for adults in New Hampshire,

“We have a lot of work to do to really figure out who this man was, why he might have done what he did, what led up to this incident,” Formella said, adding that the Haas family has requested privacy.

Haas lived in Franklin, a small city about 20 miles from Concord. He worked as a police officer for 28 years and rose to become police chief, according to the attorney general’s office.

Friday’s shooting was the latest act of violence at a U.S. hospital. Medical centers nationwide have struggled to adapt to the growing threats, which have helped make health care one of the nation’s most violent fields.

It came weeks after 18 people were killed and 13 others injured in a mass shooting in neighboring Maine.

New Hampshire House Democratic Leader Matt Wilhelm said he and fellow Democrats mourn the death of Haas.

“Our hearts are with his colleagues, staff, and volunteers at the hospital as they cope with this tragedy while continuing their critical care for our state’s mental health patients,” Wilhelm said in statement.