Police are appealing for a Good Samaritan to come forward after he helped to stop the assault of an elderly man.
The incident took place in the Market Place, Durham City, on Monday at about 3.30pm.
Police say the victim, aged in his 80s, was sat on a bench when the incident took place.
Detective Constable Lindsay Guest, from Durham Constabulary, said: “The suspect sat down next to the man and made conversation before he became agitated and assaulted the victim.
“A witness intervened and stopped the assault going any further.
“We are appealing for this man to come forward as a witness, and the victim would also like to thank him for his help.”
A 23-year-old man was arrested on suspicion of assault and released under investigation.
Anyone who saw the incident is asked to contact Durham Constabulary on 101, quoting reference number 311 of October 9.