Boca Raton, FL – Carbon monoxide poisoning was blamed Monday for the deaths of two 11-year-old girls found in a Boca Raton, Fla., house.

The sixth-grade girls were found dead Sunday morning in the home of one of the victims, identified as Amber Sue Wilson, the Palm Beach (Fla.) Post reported.

The newspaper said Amber was having a sleepover with friend at the house, where she lived with her mother, Loretta Wilson, her aunt and a younger brother.

Palm Beach County sheriff’s spokeswoman Teri Barbera said Loretta Wilson told authorities she came home Saturday night, parked her Ford Escape SUV in the garage, closed the garage door but couldn’t shut off the engine. Wilson allegedly told detectives she then went inside and fell asleep.

Barbera said the mother awoke Sunday morning to find the girls unresponsive and called paramedics before being overcome by the fumes. She was hospitalized at West Boca Medical Center where she was expected to recover, the Post said.