A major response from the emergency services was underway in Clayton, Bradford, tonight.
Ambulances and a large number of police were in the area of Clayton Road and Hollingwood Lane.
There were reports of large police cordons and officers stood guard outside properties and snickets.
One concerned resident told the T&A: "There are a lot of officers guarding houses and snickets down from Hollingwood Lane, and the air ambulance was flying over at the incident but didn't land."
The resident said there were a lot of police on the scene.
There are strong suggestions that someone has been seriously assaulted and there are also unconfirmed reports that a stabbing incident may have taken place.
Police have not issued a statement through their media channels.