HAMBURG, Pa. (AP) — Investigators say discarded smoking material caused a fire that killed a pregnant woman and her two young sons in Pennsylvania.

State police in Berks County ruled the Sept. 2 fire accidental. Police said Thursday there was no evidence of any criminal intent.

The fire originated on a first-floor rear porch at a home in Hamburg, about 55 miles (88 kilometers) northeast of the capital city, Harrisburg.

The victims were 27-year-old Jennifer Wilder and her two sons, ages 5 and 2. Officials say Wilder was about six months pregnant.

A man was able to escape by jumping from a bedroom window.