A man suffered a fractured skull following an attack which left him requiring surgery.
TeessideLive reports that the victim was left in the middle of the road, with head and facial injuries, following the early-morning assault in Stockton.
Cleveland Police is now trying to track down a taxi driver who stopped to assist the victim who is in his fifties.
The incident happened between midnight and 2am on Friday, August 13 on Yarm Lane at the junction with Bowesfield Lane.
The victim had stopped to light a cigarette when he was assaulted by "a number of males".
He ended up on the floor in the middle of the road, police say.
A Cleveland Police spokesperson said: "A passing taxi driver stopped to assist the victim and officers would like to appeal to this driver to come forward and speak with them as he may be able to assist with their enquiries.
"The victim suffered facial injuries and a fractured skull and required surgery."
Any witnesses or anyone with dash cam or CCTV footage of the incident is asked to contact Detective Constable Nigel Rusby from Stockton CID on 101, quoting incident number 136300.
Independent charity Crimestoppers can be contacted anonymously on 0800 555 111, or online at: https://crimestoppers-uk.org
In scenes of absolute chaos children with autism were left waiting hours for school buses or asked to get into taxis alone without assistants as the handover of SEN school transport from one company to another was comple