Police responded to the Franklin home at about 8 p.m. Sunday after family members found the children together inside the hope chest, which had a lid that could only be opened from the outside. The children were taken to hospitals but did not survive.
David Traub, a spokesman for Norfolk District Attorney Michael Morrissey, confirmed the deaths. He said multiple family members, including an adult, were in the house at the time. He would not say whether the adult was a parent of the children.
The chest was close to a television that had the volume turned up, Traub said.
Authorities say the deaths appear to be accidental, and relatives are cooperating with investigators.
Autopsies were scheduled, and the results will show "if the medical information corresponds with the narrative as it's emerged," Traub said.
No names were released.
No one appeared to be inside the family's ranch-style home Monday morning. Several children's bicycles were scattered in the backyard, along with a boy's truck and a plastic sled. Two bouquets of flowers and two stuffed animals - a white kitten and a brown dog - had been left on the front steps.
Both children attended an elementary school in town. School officials informed parents of the children's deaths and said counselors are available to students and staff.