A 3-year-old boy fell from a second-story window at a house in Noyac on Tuesday evening, according to Southampton Town police.
Police received a 911 call at 5:28 p.m. and the first arriving officers found the boy conscious and alert, police said in a statement.
The Sag Harbor Volunteer Ambulance Corps treated the boy at the scene. The child, whose name was not released, was airlifted to Stony Brook University Hospital, the closest level-one trauma center.
Detectives are investigating the circumstances into the incident, police said.