Three children died of smoke inhalation and carbon monoxide poisoning early Friday after fire swept through their family's townhouse in Clairton, the Allegheny County medical examiner's office has ruled.

Rachel Finn, 9, Deausha Faulk, 6, and Michael Zigler, 2, were killed in the blaze that engulfed their bedrooms while they slept in the home on Soltis Drive. Rachel and Deausha were sisters and lived in the home in the Century Towne Homes complex; Michael, their cousin, had been visiting.

Michael's older sister -- Tiarra Williams, 17 -- and the older brother of Rachel and Deausha -- Daishawn Smith, 11 -- were treated at local hospitals. They were injured but escaped from the burning home, as did the mother and sister of the girls -- Markell Finn-Faulk and her daughter, Essence, 14.

Investigators have not determined or issued a ruling on the cause of the blaze. The house was equipped with working smoke detectors, and authorities still don't know why the alarms did not roust the family in time for everyone to flee.

Looking for more from the Post-Gazette? Join PG+, our members-only web site. You'll get exclusive sports content, opinion, financial information, discounts from retailers and restaurants, and more. Our introduction to PG+ gives you all the details.