The teen was able to walk out of water and sent to the hospital, police said.
Two more shark encounters were reported on Long Island Wednesday, including an attack on a teenager, officials said.
A dead shark, which appeared to be a great white according to The Riverhead Society, was spotted on Dune Road Beach in Quogue, New York, by a nearby resident around 9:33 a.m., police said.
Later in the evening, a 16-year-old surfer suffered a minor bite on his foot while he was in the water in Kismet Beach on Fire Island, police said.
The 7- to 8-foot shark found in the morning washed back into the ocean before police could secure it, according to officials from Quogue Village Police Department.
"At this time, we are cautioning swimmers and boaters in the area to be aware of this ongoing situation," the police said in a statement.
Suffolk County Police Marine Bureau said the Fire Island sighting happened around 5:45 p.m. when the teen paddled approximately 20 yards off the shore. The surfer was bit on his right foot, and sustained an approximate 4-inch laceration, police said.
The teen was able to walk out of the water and was transported to Good Samaritan Hospital Medical Center in West Islip for treatment, according to police.
Suffolk County Police Aviation responded by helicopter, but the water was too murky to locate the shark, officials said. Marine Bureau officers continued to comb the water on boats to locate the shark, according to police.
This is the latest in a string of shark sightings and attacks off New York's coast over the last few weeks.
From June 30 to July 13, five individuals suffered non-life-threatening injuries from shark attacks near Long Island beaches, according to state officials.
On Tuesday, beaches in the Rockaways were shut down after beachgoers spotted sharks in the water. No one was hurt.
New York Gov. Kathy Hochul directed state agencies to enhance shark monitoring and patrols at Long Island beaches on Monday in response to the sightings.
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