An Uber driver has shot six people dead and wounded two more in an apparent random attack in Michigan, United States, police say.

It has been reported the shooter may have dropped-off Uber fares before the rampage, but Uber would only confirm the suspect, Jason Dalton, 45, was one of its drivers and had passed background checks.

Dalton was arrested by police after he allegedly opened fire on Sunday (AEDT), outside an apartment complex, a Kia car dealership and a Cracker Barrel restaurant over a period of little more than four hours, Kalamazoo County prosecutor Jeff Getting said.

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Mr Getting said authorities were investigating a Facebook post by the fiancee of an Uber passenger, who said that Dalton had sideswiped a car, run a stop sign and was driving erratically just before the shootings.

Mr Dalton may have been driving for Uber just before the rampage. Photo: AAP

His alleged victims included a 14-year-old girl who was seriously wounded, while four of the dead were women.

A woman who was shot multiple times at an apartment complex was in serious condition early on Sunday (local time).

Uber’s chief security officer, Joe Sullivan, said the company was contacting police to help with the investigation.

Police said the killings did not appear to target anyone in particular. 

The victims “appear to be chosen at random, because they were available,” Mr Getting said.

“They were shot multiple times, multiple — nine, 10, 11 shell casings at each of these scenes.

The 14-year-old girl initially previously reported to have been shot dead at the restaurant was in fact seriously wounded, Mr Getting said.

Kalamazoo is about 260km west of Detroit with a population of 75,000.

The carnage in Kalamazoo, was the latest in a series of mass shootings that have made gun control a campaign focus ahead of November’s US presidential election.

Dalton was arrested in downtown Kalamazoo at about 12:30am (local time Saturday) after a county sheriff’s deputy spotted him driving out of a bar parking lot.

Mr Getting said he expected Dalton to be arraigned on Monday on charges of murder, assault and firearms violations.