Douglas Foster Schneiderman, 51, of McLean, Va., was killed when his 2005 Volvo and a 1996 Ford pickup driven by Brian K. Midgett Jr. of East Hampton crashed at about 12:34 p.m., East Hampton Town Police said.
Midgett's pickup was traveling southbound when it crossed into the oncoming lane, police said.
Midgett, 20, Schneiderman's wife, Elisabeth, 51, and daughter, Rachael, 16, were airlifted to Stony Brook University Hospital with serious injuries, police said.
Schneiderman was pronounced dead at the scene.
The Schneidermans were visiting family in the area when the accident occurred, a police spokesman said.
Police said both vehicles were impounded for safety checks and the investigation is continuing.
Anyone with information on the accident can call police at 631-537-7575.