Firefighters in Toms River were called to cut the javelin without vibration before taking the victim to the hospital, initial reports said.
It was unclear whether the boy was a student observer or an athlete participating in the event.
The incident occurred about 5:40 p.m. in an open field outside Donovan Catholic High School at 711 Hooper Ave., Toms River police said.
A spokeswoman for the Toms River Police Department told NJ Advance Media that the 16-year-old boy is from Pine Beach.
The javelin was impaled several inches into his right thigh; but there was no visible bleeding, and the victim was conscious and talking to first-responders, she told NJ.com
His condition at Jersey Shore Univeristy Medical Center in Neptune had not been released.
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