WELLS – A 12-foot shark swimming close to shore Monday forced sunbathers out of the water for the second straight day.

Lifeguards were instructed to clear swimmers from the surf again on the busy, 3-mile beach after the shark was spotted at 10:30 a.m., Wells Fire Chief Marc Bellefeuille said Monday.

The closing came a day after swimmers were ordered out of the water because of another shark sighting.

Police officers were on hand to assist lifeguards in getting the word out and to make sure no one went into the water.

“They’re doing the prudent thing,” Town Manager Jonathan Carter said. There were two sharks, one of them 12 feet long, he said.

There are many sharks in the Gulf of Maine, but they rarely venture close to shore. Lifeguards are instructed to investigate shark sightings and ban swimming if they can confirm that it was a shark, Bellefeuille said.

“Our priority is the safety of the patrons on the beach,” he said. “I can’t take a chance. I’m shutting the beach down.”

The sharks were likely feeding on smaller fish that were drawn close to shore by water temperatures in the lower 70s in southern Maine, said Craig Bergeron, manager of Saco Bay Tackle.

Some visitors weren’t thrilled about being told they couldn’t take a dip in the water Sunday. But people were more accepting Monday when they realized there was a real threat.

Officials believe the sharks were either blue sharks or mako sharks. Either can be a threat to humans.

Bob Morrell, owner of Wheels and Wave, a surf shop in Wells, said most people have been understanding, even surfers who look forward to going into the water without their cold-water gear.

“We were surfing in our trunks for once,” he said before the sharks forced surfers out of the water.

There has never been a confirmed shark attack in Maine or New Hampshire, according to the Florida-based International Shark Attack File.