A gunman killed six people and seriously injured two others in the northern US state of Michigan, police said yesterday, after arresting an armed 45-year-old white male for the crime.

The suspect was apprehended at 12:40 am yesterday after a shooting rampage Saturday night at three different locations in the city of Kalamazoo, police said.

Police said the gunman seriously wounded a woman outside an apartment complex, killed two people at a car dealership and then shot to death four more and seriously wounded a teenage girl at a chain restaurant.

"What it looks like is we have somebody driving around, finding people and shooting them dead in their tracks," Kalamazoo County Undersheriff Paul Matyas told the local CNN affiliate 24 Hours News 8.

"This is your worst nightmare, when you have somebody just driving around randomly killing people," he added.

The gunman's motives were unclear, officials said.

Kalamazoo County prosecutor Jeff Getting identified the suspect as Jason Brian Dalton, 45, and said he will face murder charges in court today.

There is "no reason to believe" more than one person was involved in the crime, Getting added.

Earlier reports of the death of a seventh victim, a teenage girl who was shot at a Cracker Barrel restaurant, were incorrect, Getting added. He said the teen was "seriously, gravely injured."

A CHAIN OF SHOOTINGS

The chain of shootings began at around 6:00 pm, when the gunman opened fire on a woman who was with her three children outside an apartment complex, he said.

She was seriously wounded but is expected to survive.

The gunman next struck at 10:00 pm, killing an 18-year-old boy and an adult male at a car dealership, according to Getting.

The last and deadliest shooting came 10 to 15 minutes later at the Cracker Barrel restaurant where four more people were killed, he said.

Video at the car dealership and the restaurant helped police identify the shooter's car, Getting said.

Dalton was arrested about two hours later when a Kalamazoo sheriff's deputy saw his car leaving a local bar in downtown Kalamazoo.

"He followed the car. The Kalamazoo Department of Public Safety was able to mobilize people as a backup. They pulled the car over without incident. They were able to make an arrest of the suspect without any significant incident," Getting said.

Police seized a semi-automatic handgun and "additional evidence" from the car, the prosecutor added.

Dalton was "pretty even-tempered" during his arrest, Getting said.

Kalamazoo is located some 190 kilometers west of the industrial city of Detroit and has a population of 76,000, according to census figures.

The killings there were are the latest in a long line of mass shootings in the United States that include the December 2 massacre in San Bernardino, California that left 14 people dead and 22 wounded, and the December 14, 2012 Sandy Hook school massacre in which 20 children and six adults were shot dead.

Gun violence claims the lives of about 30,000 Americans every year and mass shootings -- rare in most countries -- have been on the rise in the United States.

According to the tracking website gunviolencearchive.org, there were 330 mass shootings in the United States in 2015, up from 281 in 2014. They affected nearly every part of the country, reaching into both big cities and small towns.