SACRAMENTO (CBS13) – Firefighters were on the scene of a fire that broke out at an apartment complex in north Sacramento Monday morning and spread to two multiple units.

The fire started in a car parked in a garage at the complex on Lexington Crossing Lane near Elkhorn Boulevard. The fire quickly climbed up to the wall and spread to the balcony and attic of a nearby apartment unit.

Two apartment units suffered heavy damage. The three residents inside were able to get out without being injured.

A resident whose car was parked next to the one that caught fire says he first thought it was a shooting.

“I heard like, a spark then I heard a boom. At first I thought someone was outside the window shooting, then I looked and I seen a fire and I was like, ‘woah,’” said Mike Siah, a resident at the apartment complex. “What panicked me was the car. We were parked right next to the car.”

The car that caught fire is owned by a mother and son. They say they don’t know why it caught fire since it hadn’t been driven for the last 7-8 hours.

Arson investigators were investigating the fire.