The 14-year-old boy was pulled from the bottom of an elevator shaft at the former New York United Hospital Center in Port Chester.
Police initially received a 911 call around 9 p.m. about a group of teenagers on the roof of the abandoned hospital.
When officers responded to the building and went to the rear of the property, they found three 14- to 16-year-old boys who frantically told them their friend had fallen through a hole in the roof.
According to the Port Chester Police Department, officers went inside the building, climbed to the roof and helped the boys to safety, while other officers tried to find the victim.
Police said the rescue was hampered by debris in the building and difficulty identifying exactly where the victim had fallen.
The teen, who dropped 60 feet down the shaft, was found around 10:40 p.m. and taken to Greenwich Hospital, where he later died.
The building has been abandoned for more than a decade.
The Port Chester Police Department Detective Bureau is investigating.
The abandoned former United Hospital has been vacant for 12 years. The 15-acre property was purchased in 2006 by Starwood Capital, and has been the subject of numerous redevelopment proposals.
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