Kansas - Kansas authorities on Friday were investigating the motives of a gunman who killed three people and wounded 14, five critically, during a 26-minute shooting spree that ended when an officer shot the suspect to death at the factory where he worked.

The gunman was served a protection from abuse order about 90 minutes before the shooting in Hesston on Thursday, and this could have triggered the incident, local media reported on Friday, citing Harvey County Sheriff T. Walton.

He would not identify the suspect, saying the name would probably be released on Friday, but a dispatcher with the sheriff's office had said the shooter was 38-year-old Cedric Ford.

Law enforcement in Hesston, a town of about 3,800 people about 36 miles north of Wichita, has said the mass killing was not terror-related.

"There were some things that triggered this particular individual," Walton said at a late evening press conference, without elaborating.

The attacker appears to have opened fire at random, although many of his victims were co-workers, Walton said.

The Kansas killings follow a mass shooting in Michigan last weekend, when a driver for car-hailing service Uber killed six people.

The escalating number of mass shootings in the United States has elevated gun control as a campaign issue in the November US presidential election.

The Kansas attacker, who was armed with a .223-caliber assault-style rifle and a pistol, fired out of his vehicle as he drove through two cities, Walton said. He then stole one victim's car and drove to Excel Industries, where he worked, and shot someone in the parking lot.

The gunman entered the lawnmower manufacturing plant, where he had been scheduled to work and where more than 100 employees were beginning the day's second shift, and opened fire on his co-workers, killing three, the sheriff said. Other employees fled in panic.

The first police officer to arrive killed the gunman after exchanging fire with him near the building's paint room, Walton said. The officer "went inside of that place and saved multiple, multiple lives," the sheriff said. "A hero, as far as I'm concerned."