Two swimmers were apparently attacked by sharks off the shores of Long Island on Tuesday, a day after two others reported being attacked while enjoying the water at popular New York beaches.

At least one beach delayed opening to holiday revelers Tuesday, after officials said drones spotted some 50 sand sharks that morning near a popular beach park. When the beach reopened, swimmers were advised to stay close to shore.

“This morning, prior to lifeguards going on duty and our authorizing swimming, we had a complete drone patrol. And right here in front of Field 3, we saw a school of sharks. There were approximately 50 sand sharks there,” Charles Gorman, New York State Parks Regional Director, told CBS New York.

The beach was closed once more after a possible shark sighting, but officials determined it was a dolphin.

Suffolk County and East End beaches are keeping a close watch on the water after more shark sightings. There were two new reports of bites Tuesday that follow two other possible attacks Monday. @DBrennanTV reports.

— CBS New York (@CBSNewYork) July 5, 2023
After a spate of attacks last year, state parks officials have increased patrols and deployed more drones to scout the waters for possible danger.

“We did have a season last year where we had six swimmers bitten from sharks, so this has turned into a bit of a concern,” Suffolk County Police Commissioner Rodney Harrison told WABC.

Tuesday’s incidents happened about 60 miles (95 kilometers) apart, including one off Fire Island Pines – not far from another attack the day before when a 15-year-old reported being bitten on one of his feet by a shark while surfing.

Earlier Monday, another 15-year-old girl was treated for an apparent shark bite to a leg.

“She didn’t see what bit her, the lifeguards didn’t know what bit her, the drone operator checked the area, we didn’t see,” Gorman said. “So we can’t definitively say what bit her.”

Tuesday’s shark encounters both occurred just before 2 p.m.