DURHAM — Investigators have figured out what caused a house fire in Durham last week. An infant died in that fire. Their mother had gone to a neighbor's house to use the phone.

Fire officials say a 2-year-old boy placed a broom inside an open oven, then took it back into the bedroom where his 9-month-old sibling lay on a mattress. The mattress ignited, starting the fatal fire.

Another neighbor rescued the 2-year-old, but was unable to reach the infant.

There is no word on whether charges will filed against the mother.