Lifeguards are on the lookout for sharks on the South Shore after a sighting on Monday and another scare Tuesday that turned out to be either a dolphin or a stingray.

Officials say a lifeguard spotted what he believed to be a shark at Jones Beach Field 6 around 3 p.m.

State officials initially told News 12 it was a confirmed shark sighting. However, an investigation by the lifeguard captain determined that it was not a shark.

"We've got to react. We've got to exercise safety. Get the swimmers out of the water so that we can scan the beaches so we can make a determination if a shark is present or not," says George Gorman, of the state Parks Department.

Officials say the beach remained closed to swimming out of an abundance of caution, but it has since reopened.

Gene Maslauskas and his son, Logan, were among dozens of swimmers ordered to get out of the water after a lifeguard spotted what had been thought be a shark.

"Any type of animal that's wild doesn't know if you're going to hurt them. They are way more scared of you than you are of the animal," says Logan Maslauskas.

MORE: 2 shark sightings close beaches along Nassau's South Shore 
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There has been a heightened state of awareness about sharks after two confirmed shark sightings were reported in the waters off Lido Beach and Long Beach on Monday.

On Tuesday, Town of Hempstead lifeguards reported seeing a shark again off the coast of Atlantic Beach.

Officials say sharks may be in the region due to warm water and more fish recently seen in the area.