An armed person walked into the lobby of a state psychiatric hospital in New Hampshire on Friday and shot dead a guard before a state police officer shot and killed the suspect, officials said.

No one else was injured in the gun violence, which erupted at about 3:30 p.m. at the New Hampshire State Hospital in Concord, the state capital, according to state police Colonel Mark Hall.

Addressing reporters at a later news briefing, Hall declined to give any information about the suspect.

He said investigators were still trying to identify the assailant.

New Hampshire Governor Chris Sununu wrote on social media that the victim was Bradley Haas, who was working security at the hospital.

Lori Weaver, commissioner for New Hampshire’s Department of Health and Human Services, said, “all patients and staff at the hospital are safe.”

Bomb squad officers were also investigating a suspicious vehicle on the hospital grounds, Hall said, without elaborating. The bloodshed unfolded quickly.

Moments after the suspect entered the lobby and shot Haas, “a state trooper assigned to the hospital and in close proximity immediately engaged, shot and killed the suspect,” Hall said.

“The entire incident was contained within the lobby of the hospital.”

Hall said additional officers were on the scene within minutes, adding that a police academy graduation was taking place on the surrounding campus at the time.

The hospital is a secure psychiatric facility where all visitors must enter through metal detectors and a police officer is always on duty, according to Manchester-based television station WMUR-TV.

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The 184-bed hospital is situated on the grounds of a 120-acre office complex that is home to several state agencies, including Health and Human Services, the Department of Education and the Public Utility Commission, WMUR said.