Mayor Bill DeBlasio on the scene says Con Ed confirms: explosion was caused by a gas leak.
3 people were taken to Jacobi Medical Center for burns.
Mayor praised work of first responders.
Investigation into cause of explosion underway.
GAS EXPLOSION ROCKS JFK HIGH SCHOOL
Emergency officials are responding to a gas explosion at JFK High.
3 People were injured.
Officials say construction had been ongoing at the school.