A 39-year-old man has been arrested on suspicion of murder after a woman was found dead and four children injured at a house in Huddersfield.
West Yorkshire Police said a 37-year-old woman was found inside a property in the Lindley area of Huddersfield with a serious stab injury after they received calls about a domestic-related incident at the address.
The woman was taken to hospital but later died from her injuries. A nine-year-old boy was also found outside the house with stab wounds to his arm.
A second nine-year old-boy, an 11-year-old boy and a six-month-old baby girl were found at the address and treated for minor injuries.
The 39-year-old man, who was detained at the scene, was also treated for serious injuries. Police said they were not looking for anyone else in connection with the incident.
Det chief insp Andy Taylor said: "Enquiries are ongoing to establish the full circumstances surrounding the incident and Neighbourhood Policing Team officers are patrolling the area, offering support and reassurance to local residents.
"I would ask any witnesses or anyone with information to contact Protective Services Crime on the non-emergency number 101 or Crimestoppers in confidence on 0800 555 111."
Police have cordoned off the area around the house on Reinwood Road as the investigation continues.