Wildwood police said emergency responders were called to a pool at the Beachside Resort at 3700 Atlantic Avenue Friday night. When they got there, people at the pool were giving the little boy CPR.
The responders took over, trying to resuscitate him, but couldn't save him.
Wildwood police and the Cape May County Prosecutors Major Crimes Unit are handling the investigation, and police are also asking people to be "extra cautious" when it comes to swimming safety.
They encourage everyone to swim near a lifeguard, especially at the beach and are reminding adults to keep a close eye on young children.
Police said life vests or flotation deivces should always be used.
They added they are "absolutely devastated" by what happened at the pool.