"This is a fairly peaceful community, and to have something like this is terrible," Walton said.
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The FBI and the federal Bureau of Alcohol, Tobacco, Firearms and Explosives were on the scene but the sheriff said the incident was not related to "terrorism."
Kansas law doesn't require a permit to buy long guns or handguns, which don't have to be registered.
Court records showed that Ford, 38, was a felon who previously lived in Miami and was on probation with a series of convictions in Florida including burglary.
He had a criminal record stretching back to October 1996, when he was charged with carrying a concealed firearm when he was 18 years old, the records showed.
Law enforcement officials first became aware of Thursday's incident after being called to reports of two people shot and injured, one in the shoulder and one in the leg, on different streets across the two towns.
The gunman then drove north toward his workplace, where he shot another person in the parking lot, according to a statement from the Harvey County Sheriff's Office.
He was "seen entering the building with a long gun" before he "opened fire inside the building," the statement said.
By the time the first police officer arrived at the scene the gunman was "actively shooting at any targets that came into his sights," Walton told a news conference.
The officer — whose agency and identity was not immediately disclosed — went in alone, killed the gunman and "saved a lot of lives," the sheriff said.
A couple of hours later, Newton police and a SWAT team converged on a home in a Newton trailer park were the gunman was believed to have lived.
Walton told reporters that the shooter's roommate was inside and refusing to engage with officers — but when officials obtained a warrant and returned at 10 p.m. they found the property empty, NBC station KSN reported.
One of those injured at Excel Industries was Dennis Britton, who was shot in the right buttock and suffered a fractured right femur, according to his father.