Researchers say a tooth taken from the leg of a boy bitten at New York's Fire Island has been identified as that of a sand tiger shark.

University of Florida researchers compared DNA from the tooth to a genetic dataset of sharks to determine its species.

In a release Wednesday, Gavin Naylor, director of the Florida Program for Shark Research, said it's the first time a shark involved in a bite has been identified using DNA.

Beaches were closed at Fire Island in mid-July after the 13-year-old boy and a 12-year-old girl were bitten.

Both children were treated and released from a hospital.

Naylor believes both bites were accidental, from juvenile sharks following schools of fish.

He says sand tigers can grow up to 500 pounds but rarely bite humans.