He has been identified as Pablo Hernandez Cruz, 49, of Mays Landing.
Authorities said two children jumped into a river in Weymouth Furnace County Park in Hamilton Township. However, swimming in the river is prohibited.
There are multiple signs posted in English and Spanish warning people not to swim.
The children started to experience some difficulty in the water, investigators said. That's when Hernandez Cruz reportedly went in to help them.
Hernandez Cruz was able to retrieve the children from the water and safely get them to shore, according to police.
However, Hernandez Cruz then went under the water. He was taken to the hospital in critical condition, but officials said Thursday morning he had passed away.
"Risking his life to save two innocent young kids," noted Jorge Fornia from Vineland.
The park was closed Wednesday but will reopen Thursday.
This is the same park where authorities say a 23-year-old man drowned in June 2021.
County officials told Action News that many people don't realize how deep the water is, which makes it dangerous for anyone who swims there.
"It blows my mind. There are signs and people -- kids and adults -- who still don't obey the rules," said Fornia.