State police say 35-year-old Joseph LaFave, of LaGrange, was driving a BMW north in the southbound lane around 2:30 p.m. near Todd Hill Road.
LaFave's vehicle collided head-on with a Lincoln Navigator driven by 69-year-old William Scheibel, of Wading River.
LaFave was pronounced deceased at the scene, while Scheibel died at a hospital.
A 67-year-old female passenger in the Lincoln suffered injuries not considered life-threatening.
The investigation is ongoing.