Police guard the front door of Excel Industries in Hesston, Kansas, where a gunman reportedly killed four people and injured many others on Thursday, Feb 25, 2016. [Photo/IC]

An employee killed up to four people and wounded as many as 20 others in a shooting spree that ended at his work site in Hesston, Kansas, on Thursday where he was shot and killed by authorities, the local sheriff told reporters.

The gunman appears to have opened fire at three locations before entering the building of a lawnmower manufacturer where he worked, Harvey County Sheriff T. Walton said at a news conference.

The shooter, identified by a dispatcher with the Sheriff's Office as 38-year-old Cedric Ford, began his attacks at about 5 pm local time (2300 GMT) in the town of Newton, where a man driving a truck was shot in the shoulder, Walton said.

Soon after, the suspect shot a person in the leg on another street on the way to his worksite at Excel Industries in Hesston, less than 9 miles (14 km) northwest of Newton, where he opened fire again in the parking lot, Walton said.

The gunman entered Excel Industries and continued his shooting spree, the sheriff said.

"This is just a horrible incident that's happened here," Walton said. "There are going to be a lot of sad people before this is all over."

The shooter killed three or four people, and wounded as many as 20 others before he was killed by authorities, the sheriff said.

The series of shootings about 35 miles (60 km) north of Wichita come less than a week after a Michigan man who worked as a driver for car-hailing service Uber was charged with killing six people during a shooting rampage.

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

A spokesman for the local Via Christi Hospital St. Francis said they have taken in six patients from the shooting, with five in serious condition and one in fair condition.

Wesley Medical Center is treating three patients, said the facility's spokeswoman Susan Burchill. She had no further details.

"Please send your thoughts and prayers to the people of Hesston tonight," Kansas Governor Sam Brownback said in a statement.

An employee at the business told local television station KSN that she was just steps away from the shooter before she made her escape.

"I've been through quite a bit but nothing like that; that's terrifying," the woman, who did not give her full name, told the station.