An 11-year-old girl, named by West Midlands Police as Jasmine Forrester, has died in hospital after being stabbed in a house in Wolverhampton.
Police said a 51-year-old man was also taken to hospital for a minor injury and has been arrested on suspicion of murder.
Superintendent Harvi Khatkar, of Wolverhampton police, said: “This is an extremely distressing incident and our sympathies go out to everyone affected.
“We are working to establish exactly what has happened, and fully understand the impact that this will have on the community.
“But we do believe this is an isolated incident, and we are not looking for anyone else.
“Extra officers will be out patrolling the area to offer reassurance to residents.”