A 73-year-old man was airlifted to Stony Brook University Hospital with serious injuries Saturday night after a 17-year-old driver rear-ended him on Bridies Path in Southampton, according to Southampton Town Police.Authorities said Justin Fisher of Southampton and his passenger, also 17, were speeding south on Bridies Path at around 9 p.m. when they struck a car being driven by Robert Egan of East Moriches, who was pulling out of a driveway.Mr. Egan had to be flown, via Suffolk County Medevac helicopter, to Stony Brook where he remains in critical condition, according to a relative. Police said earlier this week that they did not know the extent of Mr. Egan’s injuries, originally classifying them as non-life-threatening.Mr. Fisher and his passenger, who was not identified by police, were taken by ambulance to Southampton Hospital for the treatment of non-life-threatening injuries, according to police.Officers issued Mr. Fisher a speeding ticket, police said, while also noting that his view could have been obstructed by a small hill in the road.The North Sea Fire Department also responded to the scene.