The Hawaii County Fire Department said the boy suffered injuries on both legs after he was bitten Sunday afternoon southeast of Hilo. He was airlifted to Hilo Medical Center for treatment.
The boy's condition isn't clear. A call to the hospital's spokeswoman was not immediately returned.
The Hawaii Department of Land and Natural Resources closed ocean waters along the Pohoiki coastline after the attack.
Earlier Sunday, officials closed Hapuna Beach on the Big Island's northwestern shore after lifeguards spotted a shark.
On Wednesday, a shark bit off the arm of a 20-year-old German tourist who was snorkeling in Maui.
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