The two attacks took place in the surf on Fire Island within half a mile of one another less than an hour apart.
Matthew Donaldson, 13, was bitten by what is believed to be a shark off Atlantique on Fire Island when a wave knocked him off his boogie board.
"It wasn't sharp, it was just kind of a shock feel," Matthew said. "Because it was really quick, it was like one second, went like that and then it just let go immediately."
The boy "stumbled out of the water" into a lifeguard tent, where the lifeguard dressed puncture wounds, officials said. EMTs removed a piece of tooth from the boy's leg that is now being analyzed.
Town of Islip Supervisor Angie Carpenter said "it has not been totally confirmed" it was a shark bite. The head lifeguard said the lifeguards and EMT assumed it was a small shark when they found the tooth lodged in the boy's wound.
Possible shark tooth pulled from leg of 13-year-old boy bit while boogie boarding in ocean off of Atlantique beach today. Courtesy Ocean Beach Fire Dept. pic.twitter.com/REzYvYo7vQ— CeFaan Kim (@CeFaanKim) July 19, 2018
"It was small like it was from a baby shark or something like that and it was a sharp tooth. It was actually fairly sharp," Matthew said.
The boy, who was part of a town camp, is OK and was able to walk on and off a police boat before he was sent to the hospital for non-life threatening injuries.
"It's just crazy. It's incredible," lifeguard Bella Coan said. "There's never been a shark attack on Fire Island. All the older guys they've never seen this."
The second incident being investigated happened at Sailor Haven on Fire Island. In that case, 12-year-old Lola Pollina was bitten and suffered a wound to her leg.
Warning: Graphic photo
She was able to walk to shore with assistance from her dad before she was taken to the hospital. Lola said the bite didn't hurt at first and she didn't feel it. She said it only hurt when lifeguards started poking around the wound.
"I thought it was a shark. We were at the beach and there wasn't a tiger or anything," Lola said laughing about what appeared to her to be a 3 to 4 foot shark.
"It was just like a quick kind of like pull and I was kind of in like shock almost," Lola said. "Because it like pulled and then I kind of looked at it and I was like oh my gosh."
"I see her in the water struggling, her head kind of, and there was this commotion in the water next to her," Barbara Pollina, the girl's mother, said.
"My daughter was not even 10 feet off the shore up to her waist. All of the sudden I see her panicking, and I could see something -- I couldn't tell what it was, but it was kind of flapping about," Philip Pollina, the girl's father, said.
Officials with the National Parks Service say there were bite marks on the victim "consistent with a large fish," but there was not a sighting of a shark in the area and the incident is not yet confirmed as a shark bite.
The 7th-grader's wound was too deep for stitches. She plays soccer but said she didn't think her injury would impact her play.
"Both of these kids are OK and we are seeing this as an opportunity to remind everyone that the water can be dangerous, we need to be careful at all time," Carpenter said.
In a third possible shark sighting, the Superintendent at Jones Beach said swimmers were evacuated from the water at Robert Moses State Park after a lifeguard spotted a shark.
Swimmers were allowed back into the water around 2:30 p.m. when the sighting was deemed to be a sandbar shark.
New York Gov. Andrew Cuomo said he has deployed Department of Environmental Conservation Commissioner Basil Seggos to lead a multi-agency investigation into the apparent shark attacks.
"I am relieved that both teenagers who were attacked have been released from the hospital. At this time, both beaches where the attacks occurred have been temporarily closed to swimmers as the investigation continues. The State will do everything we can to protect beachgoers and keep the community safe," Cuomo said.
Officials said it is currently shark breeding season and most shark attacks happen at the surf zone.
Officials will also determine early Thursday morning if the beaches on Fire Island will be reopened.