A 12-year-old girl jumped off the roof of a burning two-story house in Hempstead Thursday, breaking her ankle as she tried to escape a blaze later deemed suspicious, authorities said.

Several adults inside the Long Beach Road home escaped without injury after flames broke about 9:45 a.m., said Michael Uttaro, Nassau County assistant chief fire marshal.

Details were not immediately available on where the fire started and whether flames blocked the girl’s route downstairs, but she was rushed to Nassau University Medical Center with non-life-threatening injuries, authorities said.

“Thankfully, a broken ankle from the roof of the house is the best case scenario for a poor kid jumping off the roof,” Uttaro said. “I guess she landed with grace. Pretty scary stuff.”

Investigators are looking into whether the fire was set after a dispute between adult residents of the house and another man, authorities said. The fire was being considered as a second-degree arson, officials said.

Uttaro said he was unaware of the dispute and that investigators from the Nassau police arson squad, Hempstead Village police and fire marshal’s office were continuing to interview witnesses Thursday night.

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The house suffered “extensive” fire damage and fire marshal investigators who examined the debris have deemed the cause suspicious, which could mean anything from arson to someone playing with matches, the fire marshals office said.

“They couldnt find any accidental cause or any other cause,” Uttaro said.

Scores of firefighters from four departments - Hempstead, West Hempstead, South Hempstead and Uniondale - put out the fire by late morning, supported by the fire marshal’s rehab unit, a truck and personnel who provided refreshments and assessed the health of firefighters in the heat.

Uttaro said no other injuries were reported.