Another shark sighting Thursday halted swimming from Point Lookout to Lido Park West Beach for about an hour on a day when feels-like temperatures are over 100 degrees.

Town of Hempstead officials made the announcement, saying lifeguards spotted what looked like a 6-foot shark.

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"There was a fin in the area. The shark was 6 to 7 feet. It was circling. It was in the sandbar about 25 yards off and that's when we decided to get everyone out of the water and take precaution," says Frank Falcone, Town of Hempstead lifeguard.

Falcone is one of five lifeguards who spotted a shark in the waters of Lido Beach West around 10:45 a.m. Falcone says they were in the middle of training when it happened.

Nassau County Executive Laura Curran says this is the 20th suspected shark sighting so far this summer. Curran says that is three times more than what Nassau reported at the same time last year.

MORE: More shark sightings reported at South Shore beaches

With the extreme heat, health official​s are advising people to stay in the shade, don't overexert yourself and drink plenty of fluids. They say signs of heat exhaustion include heavy sweating, nausea, vomiting and dizziness.