A LOUISVILLE BANK employee armed with a rifle killed five people at his workplace yesterday morning while livestreaming the attack on Instagram, authorities have said.

Police arrived as shots were still being fired inside Old National Bank and killed the gunman in an exchange of gunfire, Louisville Metro Police Department chief Jacquelyn Gwinn-Villaroel said.

The city’s mayor, Craig Greenberg, called the attack “an evil act of targeted violence”.

It is the 15th mass killing in the country this year and comes just two weeks after a former student killed three children and three adults at a Christian elementary school in Nashville, Tennessee.

In Louisville, the chief identified the gunman as 25-year-old Connor Sturgeon, who she said was livestreaming during the attack.

“That’s tragic to know that that incident was out there and captured,” Gwinn-Villaroel said.

Nine people, including two police officers, were treated for injuries from the Louisville shooting, University of Louisville Hospital spokeswoman Heather Fountaine said in an email. One of the wounded, identified as 57-year-old Deana Eckert, later died, police said last night.

One of the wounded officers, 26-year-old Nickolas Wilt, graduated from the police academy on 31 March. He was in critical condition after being shot in the head and having surgery, the police chief said. At least three patients had been discharged.

Kentucky governor Andy Beshear said he lost one of his closest friends in the shooting — Tommy Elliott — in the building not far from the minor league ballpark Louisville Slugger Field and Waterfront Park.

“Tommy Elliott helped me build my law career, helped me become governor, gave me advice on being a good dad,” said Beshear.

“He’s one of the people I talked to most in the world, and very rarely were we talking about my job. He was an incredible friend.”

Also killed in the shooting were Josh Barrick, Jim Tutt and Juliana Farmer, police said.

“These are irreplaceable, amazing individuals that a terrible act of violence tore from all of us,” the governor said.

It was the second time that Beshear was personally touched by a mass tragedy since becoming governor.

Beshear spoke as the investigation in Louisville continued and police searched for a motive. Crime scene investigators could be seen marking and photographing numerous bullet holes in the windows near the bank’s front door.

As part of the investigation, police descended on the neighbourhood where the suspect lived, about five miles south of the downtown shooting. The street was blocked as federal and local officers talked to residents.

Deputy police chief Paul Humphrey said the actions of responding police officers undoubtedly saved lives.

“This is a tragic event,” he said. “But it was the heroic response of officers that made sure that no more people were more seriously injured than what happened.”

Meta, the company that owns Facebook and Instagram, said in a statement that it had “quickly removed the livestream of this tragic incident this morning”.

Social media companies have imposed tougher rules over the past few years to prohibit violent and extremist content.

They have set up systems to remove posts and streams that violate those restrictions, but shocking material like the Louisville shooting continues to slip through the cracks, prompting politicians and other critics to lash out at the technology industry for slipshod safeguards and moderation policies.