A man has been arrested on suspicion of murdering his partner and six-year-old son, it has emerged.
The 41-year-old woman and the child were found with stab wounds at a house in Bolton-le-Sands, Lancashire.
Police said they were confronted with a "distressing scene" as they entered the property, where the body of the child was found in the front bedroom.
The 34-year-old murder suspect was also at the house in Lowlands Road and had suffered stab wounds.
He was arrested on suspicion of murder and was airlifted to the Royal Preston Hospital where his conditioned is described as serious.
A cordon remained in place at the scene and post-mortem examinations will take place later, police said.
Detective Superintendent Paul Withers, of Lancashire Police, said: "The person who is under arrest is known to the people in the house.
"It is quite a distressing scene as you can imagine, a six-year-old boy and a 41-year-old lady. We're very keen to ascertain what has happened in the house behind me.
"They've received stab wounds, I don't wish to speculate any further than that."
He added: "The little boy was upstairs in the front bedroom, and his mother is downstairs."