UPDATE: Police have charged an 18-year-old Ellenbrook man in relation to an assault in Caversham yesterday.
He is due to appear in Midland Magistrates Court on July 6 charged with endanger life, health and safety of a person.
Police still want to hear from any witnesses or from anyone with dash-cam footage.
Get in front of tomorrow's news for FREE
Journalism for the curious Australian across politics, business, culture and opinion.
READ NOWEARLIER: Police are investigating an assault between three men near Caversham Store yesterday morning.
Between 9am and 9.20am an altercation occurred on the road verge of West Swan Road.
It is alleged the altercation occurred between the men, who were the occupants of a silver Commodore and a small white utility parked nearby.
The 43-year-old driver of the Proton Jumbuck utility received head injuries and was conveyed to St John of God Hospital Midland via St John Ambulance.
The 49-year-old male driver and the 18-year-old male passenger of the 2005 silver Commodore are assisting police with their inquiries.
It is believed the altercation stemmed from an earlier traffic incident.
Police are asking for anyone who witnessed the altercation and saw the two vehicles on West Swan Road or has dash-cam footage of the area between 9am and 9.30am.
If you have any information please call Crimestoppers on 1800 333 000.
MORE: Victoria Park fuel station attendant detains alleged armed robber
MORE: Thornlie house fire: man dead, boy in critical condition
MORE: Bill Shorten makes pitch to WA voters ahead of July 28 by-elections