A man has been arrested on suspicion of murder and attempted murder, amid an investigation by counter terrorism police officers.
Officers say a man died and another was attacked in the early hours of Sunday morning 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.
Cleveland Police are being supported by Counter Terrorism Policing North East as they investigate the death and assault.
The involvement of counter-terrorism officers is due to “initial inquiries”, Cleveland Police said.
Tees Street in Hartlepool
The force said in a statement: “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.”