Joseph LaManna was driving home from an engagement party on Saturday afternoon when he heard tires screeching behind him.
He looked in the rearview mirror in time to see a vehicle fishtail out of control, then skid through a guardrail and flip, belly side up, into Huntington Harbor.
LaManna, 34, pulled over, and he and his brother, Nicholas, 38, jumped into the water after the vehicle, a 2005 Chevrolet Suburban.
The water was chest-deep, the inhabitants of the car invisible in the cold, murky harbor.
"I was trying the door handles. Everything was locked. We started punching the windows," said LaManna, of Center Moriches.
The brothers grabbed chunks of asphalt, smashing them against the submerged windows before LaManna found a big rock, plunged down into the water and finally broke through into the cabin, he said.
He said he punched the rest of the glass with his right fist, and reached in to feel for anyone in the SUV. He wondered if there were children inside.
LaManna, bleeding from cuts from the glass, went back to the shore while his brother and several other good Samaritans continued the rescue.
The passenger in the Suburban, Liam O'Mara, 20, emerged conscious but dazed, LaManna said. The driver, Edward Franz, 29, had to be extricated from the rear of the Suburban by members of the Huntington Fire Department. He was later pronounced dead at Huntington Hospital.
"Me and my family continue to pray for his family," O'Mara, of Huntington, said Sunday evening. He declined to comment further.
In addition to the LaManna brothers, the good Samaritans included Pete Keller, 43, of Huntington and Michael Fodera, 20, of Elwood, police said.
"You don't know what to do in that situation," said LaManna, a carpenter. "We just acted. That's it. I'm just very upset someone passed away."
Police said the roads were wet from rain at the time of the crash, and the investigation is continuing.