YOUNGSTOWN, Ohio (AP) — Fire officials suspect the careless use of a lighter or matches on a mattress at an Ohio home caused the fire that killed five children in December.

A Youngstown fire investigator at a news conference Thursday said the children’s mother, America Negron, was smoking while lying on a mattress on the living room floor watching television. Investigator Kurt Wright says the fire has been ruled accidental with the cause undetermined.

Negron escaped by jumping from a second-floor window and was hospitalized with critical injuries.

The bodies of three children, ages 9, 3 and 2, were found on the second-floor of the home. The bodies of 1-year-old twins were found on the first floor.

Negron told WKBN-TV last week it feels like she’s living “in hell” without her children.