Cleveland Police are investigating the death of a man and the assault of another in the early hours of Sunday 15 October 2023 in the Tees Street area of Hartlepool.
A 44 year old man has been arrested on suspicion of murder and attempted murder and remains in custody.
Due to initial inquiries into the circumstances of the incident, Cleveland Police are working with Counter Terrorism Policing North East on the investigation.
Counter Terrorism Policing has deployed its specialist capabilities to help establish what happened.
It is not believed that there is any outstanding threat to the public and the local community connected to this incident.
A cordon remains in place and a search is ongoing at a property in the area.
The man who was assaulted was taken to hospital and remains there with what are believed to be non-life threatening injuries.