Seattle police arrested a 29-year-old man early Tuesday for investigation of assault after he claimed a gun he was carrying accidentally went off, wounding his rideshare driver.

Officers were dispatched to Fourth Avenue North and Mercer Street, in the Lower Queen Anne neighborhood, at 3:15 a.m. after receiving a report of a shooting. They arrived to find the suspect lying on the ground next to a bronze Nissan Altima with a gun on the roof of the car.

The driver of the vehicle, also 29, had been shot in the lower back. He was taken by Seattle Fire Department paramedics to Harborview Medical Center in serious condition, police said.

The suspect told officers that the gun he was carrying went off as he was exiting the car. Police said he was not carrying the firearm in a holster, but that he had a valid conceal carry permit.

The man was booked into the King County Jail.