Three staffers at UPMC Memorial Hospital in Pennsylvania, including a doctor, a nurse and a custodian, and two other officers were shot and wounded in the attack, York County District Attorney Tim Barker said.
A fourth staff member was injured during a fall, Barker said.
Gunfire erupted after officers from several different agencies went to engage the shooter, who Barker identified as Diogenes Archangel-Ortiz, 49.
He said Archangel-Ortiz was holding at gunpoint a female staff member hostage who had her hands tied with zip ties when police opened fire.
"This is a huge loss to our community," Barker said at a press conference on Saturday.
"It is absolutely clear, and beyond any and all doubt, that the officers were justified in taking their action using deadly force."
The officer who died in the shooting was identified as Andrew Duarte of the West York Borough Police Department.
"We all have broken hearts and are grieving at his loss," West York Borough Manager Shawn Mauck told The Associated Press.
Duarte was a law enforcement veteran who joined the West York Borough Police Department in 2022 after five years with the Denver Police Department in Colorado, according to his LinkedIn profile.
He described receiving a "hero award" in 2021 from Mothers Against Drunk Driving for his work in impaired driving enforcement for the state of Colorado.
"I have a type A personality and like to succeed in all that I do," his LinkedIn profile said.
UPMC Memorial is a five-story, 104-bed hospital that opened in 2019 in York, a city of about 40,000 people known for its creation of York Peppermint Patties in 1940.
The shooting is part of a wave of gun violence in recent years that has swept through US hospitals and medical centres, which have struggled to adapt to the growing threats.Â
Such attacks have helped make health care one of the nation's most violent fields, with workers suffering more non-fatal injuries from workplace violence than workers in any other profession, according to the US Centers for Disease Control and Prevention.
