A man arrested after six people were killed in a series of apparently random shootings in a Michigan city was a driver for online taxi service Uber.

Police are questioning 45-year-old Jason Dalton, of Kalamazoo County, following the attacks that took place over the course of more than four hours.

Authorities are investigating a Facebook post that suggested the suspect was driving erratically around the time of the shootings on Saturday.

Officers said a gunman opened fire about 6pm on an apartment building in the city of Kalamazoo where a woman was left severely injured after being shot many times.

About four hours later, a father and his 18-year-old son were shot dead while looking at vehicles at a car dealership, according to authorities.

About 15 minutes after that, four people were killed and a 14-year-old girl was seriously injured after the gunman shot at the victims sitting in two cars in a restaurant car park.

Kalamazoo County prosecutor Jeff Getting said the victims "appear to be chosen at random, because they were available".

He added: "They were shot multiple times, multiple - nine, 10, 11 shell casings at each of these scenes".

Kalamazoo County Undersheriff Paul Matyas revealed the threat was now over but also said of the attacks: "There's no common denominator with any of these.

"This person was just waiting in the parking lot of the apartment complex. The one at...the dealership, they were looking at cars. The ones at Cracker Barrel, they were just sitting in their cars".

Mr Getting said Dalton will likely face multiple counts of first-degree murder and attempted murder.

An Uber representative confirmed Dalton was a driver for the taxi service and said he had passed background checks.