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THE BRONX — Three private contractors sustained serious burns after an explosion rocked John F. Kennedy High School in the Bronx Thursday evening.

FDNY, NYPD and OEM all responded to the school, located at 99 Terrace View Ave. — which suffered heavy structural damage to the fourth, fifth, and sixth floors in the blast.

“What we have here at JFK High School is a shocking scene,” Mayor Bill de Blasio said in a press conference Thursday.

According to NYC School Construction Authority’s website, workers were building a new science lab inside the school.

One victim was transported to Jacobi Medical Center in serious condition with burns. Two others’ injuries are being examined.

FDNY and NYPD also searched debris that fell in the blast and found no other victims. Gas at the building has been shut off.

De Blasio said the Buildings Department will check the structural integrity of the school.

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