ROSEBURG, Ore. (AP) — A 49-year-old man has been arrested in connection with a series of highway shootings in southwest Oregon, state police said.

Kenneth Ayers, of Roseburg, was arrested on suspicion of attempted murder, assault, recklessly endangering another person and other charges, police said. It wasn’t immediately known if he has an attorney to comment on his behalf.

At least eight vehicles have been struck by bullets on Interstate 5 since the end of May, police said. The most recent shooting happened Wednesday in Jackson County when a woman in a vehicle was struck by a bullet, police said. She has since been released from the hospital.

It was the first known injury, police said.

Police had been investigating a possible link between the shootings and a UPS truck when they found Ayers north of the spot where the woman was hit, Oregon State Police Capt. Tim Fox told The Oregonian/OregonLive. Police found a gun in his truck consistent with the gun used in the shootings, Fox said.

Police said Ayers was a UPS employee.

“We are appalled to hear about these allegations and are fully cooperating with the responding authorities,” a UPS spokesperson told the newspaper.

Police have yet to determine a motive. Troopers believe the shootings began May 12, shortly after Ayers’ route was changed and sent him south of Roseburg on Interstate 5.