Four killed in US birthday party mass shooting

Police heard shots being fired when they arrived at a home in Florence early Saturday, said Jeff Mallery, the city's police chief.

Police found seven shooting victims at the home, Mallery told media during a news conference.

Four people were found dead, police said.

Three people were taken to a hospital in Cincinnati in critical condition.

They were expected to recover, Mallery said.

The suspect led police on a chase that ended after his vehicle went off a road and fell into a ditch.

The suspect had a self-inflicted gunshot wound and died at a hospital, police said.

Police said the suspect acted alone, and there was no ongoing threat to the public.

The gunman led police on a chase before crashing into a ditch. (AP PHOTO)

People had gathered at the home for a birthday party for the 21-year-old son of the home owner, Mallery said.

The home owner died in the shooting, the police chief said.

It appeared that the 20-year-old suspect knew people at the party but he had not been invited, Mallery said.

A motive was under investigation.

"I know what's going on throughout the nation, but this is the first time that we've had a mass shooting in Florence," Mallery said.

"Yeah, it is very emotional. My emotions are for the victims, their families, the officers that responded, everybody that was touched by this situation."

A neighbour, Leah Moore, told The Associated Press that she heard what she thought was firecrackers at about 2am. Later, she was awakened again by police lights.

"I saw crime tape, I saw a bunch of cops, I saw all the kids in one of my neighbours' yards across the street," Moore said in a phone interview.

Moore said she knew Parrett and her family well, describing them as "great, amazing people."

"She is so wholesome, so welcoming, and she is the best person I've ever met," Moore said.

Florence is a city of about 36,000 people located about 19km south of Cincinnati, Ohio.