A Windsor man was arrested after a Santa Rosa police officer pulled him over late Thursday night and found a loaded semi-automatic handgun and drugs in his car, authorities said.

About 11:55 p.m., a Santa Rosa police officer stopped a black Audi sedan near Sebastopol Road and McMinn Avenue for a vehicle code violation. After talking to the driver, Brian Ohalloran, 34, the officer “became concerned” Ohalloran might have a weapon on him, the Santa Rosa Police Department said.

The officer searched Ohalloran’s car and found a semi-automatic handgun with an attached loaded magazine and a round of ammunition in its chamber in a backpack in the back passenger seat, police said. The officer also found another loaded magazine, methamphetamine and narcotic paraphernalia in the backpack, police said.

Ohalloran was arrested and booked into Sonoma County Jail on suspicion of carrying a concealed firearm in a car, carrying a loaded firearm, being a narcotic addict in possession of a firearm, possessing a controlled substance while armed, possessing a controlled substance and possessing drug paraphernalia.

You can reach Staff Writer J.D. Morris at 707-521-5337 or jd.morris@pressdemocrat.com. On Twitter @thejdmorris.