Police say a man fired blanks from a handgun all because a driver flashed their lights at him.
The two men were in a white Hyundai Getz travelling east on Dodd Street in Hamilton Hill when the driver of a silver Hyundai Elantra flashed their lights.
Police will allege the passenger in the Getz got out and fired between four and six shots at the Elantra.
It is then alleged the driver of the Elantra then followed the Getz as its passenger fired more shots.
Police stopped the Getz on Marine Terrace in Fremantle a short time later and found a replica handgun, several rounds of blank ammunition, cannabis and heroin.
A 49-year-old man from South Fremantle was charged with possessing heroin while a47-year-old man from Willagee was charged with going armed in a way that may cause fear.