The Associated Press reports four people were on board. The crash was reported to the Coast Guard around 2:50 p.m.
Search efforts have been suspended for the two people who remain missing after a deadly plane crash in the waters off Amagansett.
In addition to famed Hamptons home builder Krupinski, 70 - whose A-list clients included Martha Stewart and Billy Joel - those aboard included his wife, Bonnie Bistrian Krupinski, also 70; their 22-year-old grandson, Will Maerov; and pilot Jon Dollard, 47.
The crash reportedly occurred during a storm that prevented the plane from staying in contact with an airport control tower.
The cause of the plane crash remains unclear.
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The plane, a twin-engine Piper PA-31 Navajo, plunged into the water roughly a mile and a half from Indian Wells Beach Saturday afternoon.
Mr. O'Hare could not identify a cause of the plane crash, only offering that it was around the time that thunderstorms had entered the area.
Sector Long Island Sound issued an Urgent Marine Information Broadcast notice to mariners, requesting boats in the area to keep a sharp lookout for the crashed plane and any survivors.
The Coast Guard responded with Coast Guard cutters and a Sikorsky MH-60 Jayhawk helicopter from Air Station Cape Cod.
In a separate statement, Amos Goodman, chairman for the East Hampton Town Republican Committee, said, "Bonnie and Ben Krupinski were two great pillars of our community, who embodied the values of our town: generosity, warmth, charity, kindness, and hard work". A debris field was found in the ocean off of Indian Wells Beach.