Two men got out of their car in peak-hour traffic on the Hawke's Bay Expressway and assaulted another driver in what appears to be an act of road rage, police say.
A police spokeswoman said they were called to the incident near Waiohiki on State Highway 2, between Pakowhai and Evenden Rds, at 5.05pm on Tuesday.
The spokeswoman said two men got out of their car and are believed to have assaulted a person in the car behind them.
A witness who saw the incident happen in his rear mirrors said it occurred in the southbound lane just past the roundabout with Pakowhai Rd where two lanes merge.
He said two men, who he estimates were in their 20s, jumped out of the car and "punched in the driver's window of the car that they forced to stop".