A woman and her two "bubbly and nice" children have been found dead in a house in Allerton Bywater, near Leeds, police said.
They were found after West Yorkshire Police officers were called to the address in Beeston Way at 11.49am after concerns were raised for the occupants.
Neighbours said they believed the children were a girl, aged around 11, and a boy of around six.
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."
Wesley Rice, 38, lives on the estate with his partner and their two children.
He said he met the family at Halloween when they called at their house to go trick or treating.
He added: "This kind of thing just doesn't happen. To have something like this happen so close to home is shocking."
Mr Rice said people living on the estate were mainly young professional couples with young children, and that it was a "lovely area".
Police vehicles surrounded the area in Beeston Way, while forensic officers were seen entering and leaving through the red front door of the mid-terrace property.