A tractor-trailer traveling on the New York State Thruway crossed the median near Exit 16 and killed a family of three Tuesday. According to police, the driver of the tractor-trailer was heading southbound around 1 p.m. when he crossed over the median into northbound traffic. The tractor-trailer crashed into a Land Rover carrying a family of three from Rochester. The Land Rover then hit a truck carrying cars. The 4-year-old and his parents all died in the accident. The driver of the tractor-trailer later died at Westchester County Medical Center.Investigators say they will follow tire marks and check debris to see how the crash might have happened.