(Reuters) – A Michigan man who worked as an Uber driver was under arrest on Sunday in the fatal shooting of six people in Kalamazoo, as police investigated reports he may have driven customers of the car-hailing service the night of the rampage.

Prosecutors alleged that Jason Dalton, 45, opened fire, apparently at random, in parking lots outside an apartment building, a car dealership and at a Cracker Barrel restaurant in Kalamazoo, about 150 miles west of Detroit.

Two other people were wounded, including a teenage girl who was initially thought to have died.

Authorities could not confirm Dalton was working for Uber during the nearly five-hour shooting spree on Saturday evening. He was arrested without incident on Sunday while driving away from the parking lot of an area bar.

An Uber representative confirmed that Dalton was a company driver and had passed background checks. The representative referred questions about whether Dalton was working at the time of the shootings to police.

The victims “appear to be chosen at random, because they were available,” Kalamazoo County Prosecuting Attorney Jeff Getting said. “They were shot multiple times, multiple – nine, 10, 11 shell casings at each of these scenes.”

The carnage in Kalamazoo, a city of about 75,000 people, was the latest in a series of mass shootings that have elevated gun control as a campaign issue in the November U.S. presidential election.

The attack also prompted renewed interest in how Uber vets drivers, who use their personal vehicles to ferry customers at prices that are generally below those of established taxi companies. Critics say the company’s vetting process is flawed because it never meets with potential drivers in person.

Uber says on its website that it has an “extensive” driver screening process that includes collecting detailed information from potential drivers and using the investigation service Checkr to vet them. Other websites and databases such at the Dru Sjodin National Sex Offender Public Website are used as well.

WOOD-TV, a Grand Rapids station, quoted police as saying they were investigating reports Dalton dropped off Uber fares at a hotel and then killed four women and wounded a 14-year-old girl at the nearby Cracker Barrel. The teenager was in critical condition, Michigan State Police said.

In an emailed statement, Uber’s chief security officer, Joe Sullivan, said the company was in contact with police to help with the investigation.

An Uber passenger, Matt Mellen, told CBS TV affiliate WWMT that he had tried to alert the company after a wild ride with Dalton about an hour before the first shooting was reported.

He said Dalton introduced himself using a different name from the one listed as a driver. He then sped through medians and across a lawn, and Mellen jumped out at a stop at about 4:30 p.m.

“He just kind of kept looking at me like, ‘Don’t you want to get to your friend’s house?’ and I’m like, ‘I want to get there alive,'” said Mellen, a brewery worker.

His fiancée posted a Facebook account of the ride that said Dalton had sideswiped a car and run a stop sign. Mellen said he unsuccessfully tried to contact Uber about Dalton after talking to police.

Kalamazoo Police Chief Jeff Hadley told Reuters that investigators were still looking into reports of Dalton picking up Uber fares around the time of the shootings. He confirmed that a man did call police with a report of an erratic Uber driver and the report was relayed to patrol officers.

Hadley said it was not unusual for police to receive such reports and that he was not sure whether investigators had contacted the passenger who made the report.

An Uber spokesman could not be immediately reached for comment on Mellen’s account.

Michigan State Police said the carnage began at about 5:30 p.m. ET with the report of a woman wounded outside an apartment building. At about 10 p.m., a father and son were killed at the car dealership.

Dalton allegedly opened fire outside the restaurant about 15 minutes later. The four slain women were identified as Mary Lou Nye, 62, of Baroda, Michigan; and Dorothy Brown, 74; Barbara Hawthorne, 68; and Mary Jo Nye, 60, all of Battle Creek, Michigan, state police said.

Earlier, authorities reported seven deaths. Hadley said he understood that the wounded teenage girl was initially believed to have died and was being prepped for organ harvesting when she grasped the hand of one of her parents.

Getting said Dalton was thought to have been in contact with more than one person via cellphone during the shooting spree. Hadley said authorities have contacted Dalton’s wife, who is safe and cooperating with investigators.

Dalton is expected to be arraigned on Monday on charges of murder, assault and firearms violations, the prosecutor said. Getting said a semiautomatic pistol was found in Dalton’s car. Police said he had no known criminal record.

The Detroit Free Press newspaper said neighbors described Dalton as a father of two who “loved guns” and who worked on cars and had a day job as an insurance salesman.

The Kalamazoo shootings come as Uber is facing a range of regulatory and safety issues. The company agreed last month to pay $28.5 million to settle federal litigation brought by customers who alleged the service misrepresented the quality of its safety practices and fees.

(Reporting by Chris Michaud and Ian Simpson in Washington, and Curtis Skinner in San Francisco; Editing by Alan Crosby, Jonathan Oatis and Chris Reese)