PHILADELPHIA (CBS) — A former police officer in Montgomery County is under arrest on charges he fired into a car that may have been involved in a road rage incident.

The incident happened just before 10 p.m. on Feb. 18. in Upper Gwynedd Township.

Officials say Owen Farmer, 45, fired three shots into BMW after his stepdaughter, Amber Shank, told him the driver was following her home.

Shank, 20, allegedly called Farmer and told him he “needed to come outside with his gun.”

Farmer’s stepdaughter said the BMW looked like it was going to turn, then the driver veered back into the road.

The driver of the BMW says Shank was tailgating her and flipped her middle finger as she passed.

Shank reported that once she approached her house, Farmer approached the BMW and said, “what the (expletive)” to the driver.

Shank said as the BMW was turning down the street, her stepfather fired three gunshots at the vehicle.

Authorities say the driver of the BMW, Elam Campos, was driving with her teen daughter and husband at the time.

Compos told authorities as she drove from the area she heard the glass in the rear of the vehicle shatter. She then drove to Einstein Hospital after her daughter said she was hurt.

Authorities say the 15-year-old girl was struck by a single bullet while she was sitting in the front seat. She was treated for the wound and released from the hospital.

Farmer told police that after the BMW turned in front of his home, the vehicle drove over his foot, and that is when he fired the three shots.

Upon arrival, police say they found Farmer seated on the roadway outside on the 1900 block of Second Street. They say he was holding a Glock model 23.

Officers say they observed shell casings and broken glass on the roadway.

Authorities took Farmer to the hospital to be treated for a broken foot.

According to the District Attorney’s office, Farmer was a police officer with the Upper Gwynedd police department from 2000 to 2009. He was given honorable discharge.

Farmer has been charged with aggravated assault, simple assault and recklessly endangering another person.

He’s free on $50,000 unsecured bail, with a preliminary hearing scheduled for next month.