Detectives have launched a murder investigation after the bodies of a woman and her two "bubbly and nice" children were found in a house.
They were discovered after West Yorkshire Police officers were called to the address in Beeston Way in Allerton Bywater, near Leeds at 11.49am following concerns being raised for the occupants.
Neighbours said they believed the children were a girl, aged around 11, and a boy of around six.
Police say the youngsters' bodies were found upstairs in the property, while the woman was found downstairs. All three deaths are being treated as suspicious.
Detective Chief Inspector Warren Stevenson, of the force's Homicide and Major Enquiry Team, said: "The investigation is in its early stages and positive identification of the victims is still to be completed. We are currently in the process of informing family members and will not be able to publicly confirm the identities of the victims at this stage."
"Post-mortem examinations are yet to take place to establish the causes of their deaths but the victims have died in suspicious circumstances and therefore we are treating their deaths as murder."
He added the "indications" were that it was a domestic incident and that extensive inquiries were under way.
Sean Firth, 44, and his 11-year-old daughter Chloe live in a building across the road from the house.
In tears, Chloe described how she played outside in the estate with the girl.
She said: "I just feel really upset and really shocked. I never thought anything like this would really happen."
She added: "They were really bubbly and nice and kind. She was just my friend."
Mr Firth said he believed there had been some kind of domestic incident at the house around a year ago when the children's father was taken away in a police car.
He added: "I only really knew them through passing in the street and playing in the park with my daughter.
"They were nice and friendly, as far as I can make out. My daughter was devastated when she came home from school."
Anyone with any information, or anyone who witnessed anything in the area of the address leading up to the time the bodies were discovered is asked to contact the Homicide and Major Enquiry Team via 101.