PHILADELPHIA (AP) — Authorities say a woman and her three children found dead after a row home fire in North Philadelphia over the weekend died of carbon monoxide poisoning.

The Philadelphia Department of Health identified victims as Betzaida Suarez and Alexander Montanez, Yanely Martinez, and Yoniel Martinez, who ranged in age from 8 to 18.

The deaths of all four were ruled accidental. Crews were called to the blaze at the row home in the Kensington neighborhood shortly before 8 a.m. Saturday and reported heavy flames and smoke coming from the first and second floors of the row home. The cause of the blaze remains under investigation.