Suffolk County police investigators haven't said what ignited the Shirley house fire that killed a mother and her three children, but they ruled the blaze accidental Saturday.

The Oct. 11 fire began in the living room of the single-story home, taking the lives of Jennifer McCusker, 41; Aidan Tarbell, 7; and 2-year-old twins Brendan and Ava Jane Mistretta.

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The medical examiner determined the cause of the deaths was a combination of smoke inhalation and burns, police said.

The mother was found holding one of the twins in a rear bedroom. She apparently had tried to grab the children and carry them from the house.

The funeral for McCusker and her children was held Friday at St. Jude Roman Catholic Church in Mastic Beach.