A man was injured after an incident at a house in Hartlepool on Saturday night.
At least five police vehicles were turned out to an incident in Marshall Close in the Whin Meadows area of the town.
The incident happened at around 8pm.
A spokesman for the North East Ambulance Service said a 19-year-old man was taken to James Cook University Hospital.
He added: "The extent of his injuries are not yet known."
Police were still carrying out inquiries in the area today.
A spokesman for Cleveland Police wished to make no comment on the nature of the incident and would not comment on reports that it involved a stabbing.
A resident in the quiet cul-de-sac who did not want to be named said the incident happened at around 9pm
He said three police vans, two police cars and two ambulances were called to the scene.
He added: "They were there for about two hours and then put a man in ambulance.
"I don't really know the people who live there. They keep themselves to themselves."
Police are still on scene as well as forensic experts