At around 3.30pm on Friday 7 August, police were called to a report that a BMW X5 and a Peugeot 207 had been involved in a collision on Southcliffe Road, Stockport.
Following the collision, the driver of the BMW is believed to have been attacked with a hammer.
The BMW then drove off in the direction of Coniston Road, Stockport and the Peugeot drove off towards Broomfield Drive, Stockport.
Police Constable Matthew Delaney, of GMP’s Stockport Divison, said: “This appears to have been an isolated but particularly violent incident.
“Enquiries remain ongoing but I want to take this opportunity to appeal to anyone who may have been in the area at the time, who may have witnessed the incident or seen the two vehicles prior to or following the incident.
“Were you in the area at the time? Did you see the cars involved or witness the two men in the street? Please get in touch if you have any information that could help us with our enquiries.”
Anyone with information should contact police on 0161 856 9663 quoting incident 002205 of 07/08/20 or the independent charity – Crimestoppers, anonymously, on 0800 555 111.