A man is in hospital with serious injuries following an alleged assault near The High Crown pub on Front Street in Chester le Street.
It happened between 3am and 4am on Bank Holiday Monday, 27 August.
Another man is currently in custody and is assisting officers with their enquiries. Both men are from the Pelton area of County Durham.
Police believed that it is an isolated incident.
Detective Inspector Tonya Cook, of Durham Constabulary, said: