A teenager was 'punched, kicked and pushed' into a road during an attack in Gloucester city centre on Tuesday 17 January.
A motorist had to break to avoid hitting him.
It was reported that at around 4.20pm a teenage boy was assaulted by two people in the area of a footpath and grass verge outside a block of houses on Eastern Avenue.
This was between the junction of Coney Hill Road and the roundabout at Painswick Road.
An ambulance was called and the victim was checked over by paramedics having sustained cuts and bruises.
A 16-year-old boy and a 17-year-old girl, both from Gloucester, have been arrested on suspicion of assault occasioning actual bodily harm. They remain in police custody.
It is understood that those involved are known to each other.
Officers from Gloucestershire Police investigating the incident are now appealing for the motorist who stopped to come forward as they may have information which could assist.
No further details have been provided about the vehicle.
The force is also keen to hear from anyone else who was driving on the road around the time and saw what happened or anyone who has dashcam footage.
Anyone with information is asked to complete this form and quote incident 338 of 17 January.