A 23-year-old Petaluma resident was arrested Saturday on suspicion of brandishing a gun while driving, Santa Rosa police said. 

Police said they were notified around 4:50 p.m. about a man in a silver BMW flashing a gun near West 3rd Street and Amador Drive in Santa Rosa. 

Witnesses told police the man in the BMW pointed the gun at another driver after a road rage incident. 

Santa Rosa police said they were able to find the vehicle not long after thanks to witness descriptions. A traffic stop was then conducted near Stony Point and Occidental roads. 

Police identified the driver as 23-year-old Kalvin Crump of Petaluma. Crump's 1-month-old child and the child's mother were in the vehicle, as well. 

Police said a backpack containing a gun was found near the back of the vehicle, in the rear hatch area. According to police, the gun was loaded, there was an extra loaded magazine, a holster and additional ammunition in the backpack. 

The backpack was stored in a place that would have been accessible to the people in the car, police said. 

Crump was arrested on suspicion of assault with a firearm, brandishing a firearm at a vehicle, carrying a concealed firearm in a vehicle, and carrying a loaded firearm in public. 

Police said the woman and infant were released at the scene.