Suffolk County police said the crash happened Sunday morning on the Long Island Expressway, near Manorville.
Among those killed was Scott Martella, 29, of Northport, a communications director for Suffolk County Executive Steve Bellone and a former aide to Cuomo.
“Scott dedicated his all too brief life to public service and to helping others,” Bellone said in a statement. “He is known across Long Island as a leader and a great man.”
Police said the driver of an eastbound Subaru Outback, Carmelo Pinales, 26, of Hicksville, apparently lost control of his vehicle, which crossed over the grassy median, went airborne and struck two vehicles, a BMW and a Honda, that were traveling westbound.
Pinales and his 27-year-old sister, Patricia Pinales, of Westbury, were pronounced dead at the scene. His 10-year-old son, Christopher, was taken to a hospital, where he later died. Two others in that vehicle, including Patricia’s 3-year-old daughter, were injured.
A passenger in the BMW, Isidore Adelson, 81, of Westhampton, was taken to a hospital, where he succumbed to his injuries late Sunday. Three others in the BMW, including Adelson’s wife, were injured.
Martella, who was driving the Honda, was pronounced dead at the scene. His 29-year-old fiancé, Shelbi Thurau, of Northport, was injured.
Cuomo, a Democrat, said Martella served in his administration for more than four years.
“Scott was always full of big ideas to help solve the toughest challenges of the day, and he was deeply respected for his strong work ethic, candor and fighting spirit,” Cuomo said in a statement. “Long Island is a better place today because of his service and dedication to the community.” The investigation into the crash is ongoing.