A 70-year-old man has been assaulted in a road rage incident, with his attackers then turning on the bystander who went to his aid in Queanbeyan.

About 10.10pm on Saturday, the older man was driving on Southbar Road when a grey Honda Accord sedan behind his car began driving in an erratic manner before overtaking him and slowing down.

Three men in the Honda verbally threatened the man when the cars reached Donald Road.

The Honda then followed the older man to Cameron Road where the three got out of their car and threatened him again.

One of the men then struck the 70-year-old in the back of the head with a garden shovel, causing him to fall. The older man was then kicked and punched to the ground by the three men.

A 43-year-old man who witnessed the attack attempted to intervene but was also assaulted by the men.

The 70-year-old suffered bruised ribs and a cut to the head which needed stitches while the 43-year-old man was treated for a bleeding nose, and bruising and swelling to his face and ribs.

The attackers are described as being aged between 20 and 30 years old, with medium builds, and olive skin and dark hair.

Motorists with dashcam footage who may have been in the area at the time or anyone else with information about the incident is urged to contact Crime Stoppers.