Police say the 10-year boy was pronounced dead early Saturday morning.
According to police, the boy was swimming in the waters off the Cedarhurst Yacht Club at Daniel Cox Road when one of his legs came into contact with a boat's propeller.
The boy was rushed to a trauma center Friday night after paramedics on boats and jet skis rushed to try and save him.
It happened in a stretch of water known as Reynolds Channel.
It's where rescuers tell Eyewitness News the boy was struck by the propeller of a boat that had been towing him on an inflatable tube. It's a practice commonly known as "tubing."
"Every second counts (with blood loss)," said Commissioner Scott Kemins, Long Beach Volunteer Fire Department.
Rescuers from Long Beach Volunteer Fire Department were training just a short distance away. They were one of the five agencies that raced to the scene.
"Rescuers underneath his back and his head to hold him up above water obviously so he could breath and others were trying to remove his leg from the propeller assembly," Kemins said, "It was definitely in there very deep and it caused a severe laceration to his leg, he had to be extricated from the propeller."
The child was later stabilized, then rushed to Long Island Jewish Medical Center.
"Some of our members were shaken by it and but we've spoken with them and are making sure they get the psychological help they may need," Lipschitz said.
"It takes a toll on everyone, especially if you're a rescuer and you have your own children at home, it hits home," Kemins said.