Police were called to the property in the village of Little Lever, Greater Manchester, shortly before 3.50pm on Monday.
It followed reports of concern for the welfare of a woman, police said.
Officers attended and discovered the bodies of the woman and two young children.
It is understood the woman is the children’s mother.
A cordon is in place and police are investigating the circumstances surrounding the deaths.
Sean Hornby, a local councillor, told the Bolton News: “This is devastating news. I have spoken to residents in the area they are obviously shocked and very upset.”