The Maine Marine Patrol continued patrolling the coastal waters around Harpswell on Wednesday and urged beachgoers and others to stay out of the water or use extra caution following the state’s first fatal shark attack.

A shark sighting near Cousins Island in Yarmouth in the afternoon triggered an alert from the town of Cumberland. “Out of an abundance of caution, we are advising that residents do not enter the water at Broad Cove Reserve beyond ankle-deep,” the town’s alert said.

Julie Dimperio, shown in 2012 in New York City, was killed in a shark attack off Bailey Island on Monday. Dario Cantatore/Getty Images

Cousins Island lies west of Harpswell in Casco Bay.

The Maine Department of Marine Resources said it also received two other reports of shark sightings Wednesday, both near Popham Beach in Phippsburg. The marine patrol was using boats and aircraft to scan the Casco Bay region for sharks for a second day Wednesday, but the patrols were not able to substantiate any of the three reports, said Jeff Nichols, a spokesman for the department.

He didn’t know who had reported the shark sightings, or whether the sightings were made from a boat or from shore. DMR officials will meet Thursday to discuss the reports and consider what actions to take, Nichols said.

Julie Dimperio Holowach, 63, a seasonal resident of Bailey Island in Harpswell, was killed Monday by a great white shark that attacked her as she swam 20 yards from shore with her daughter, who was not injured.

The unprecedented attack shocked the small seaside community, where Holowach was remembered Wednesday as a vibrant, accomplished and down-to-earth woman who loved the ocean and nature and had endeared herself to many of her neighbors, especially fellow members of the garden club.

In the wake of the attack, state beaches prohibited swimmers from going into the ocean beyond waist-deep water.

Harpswell on Wednesday advised swimmers “to use the utmost caution” and recommended they not go farther than waist deep. “Be especially aware of your surroundings while swimming or recreating in the water and avoid going near seals or schools of fish,” town officials advised on the municipal website.

The Yarmouth harbormaster issued an email alert Wednesday night, saying that “swimming/recreating in this area is at your own risk, and should be done with strong situational awareness given the recent shark attack in Harpswell.”

The Department of Marine Resources issued warnings to anyone swimming or using paddle crafts, such as kayaks or paddle boards. Commissioner Patrick Keliher said Tuesday that such a rare attack didn’t warrant beach closures, but he urged people to be aware of their surroundings at all times in the water.

The marine patrol asked that any shark sightings be reported to marine patrol officers, including the specific location with GPS coordinates, if possible. Photos and video provided to marine patrol will help confirm the species of shark.

White sharks have been spotted in Maine for decades and spend time feeding off the Maine coast in summer and fall, but encounters with humans are rare. Shark experts say the fatal attack is the result of rebounding great white shark and seal populations along the coast.

State officials say it’s possible the shark mistook Holowach, who was wearing a wet suit, for a seal.

“We have gotten reports of seals with wounds that appear to be consistent with shark bites,” said Nichols, the Department of Marine Resources spokesman.

A seal was found off Phippsburg on Sunday with a 19-inch shark wound that was likely the work of a great white, said James Sulikowski, a professor with Arizona State University who conducts research in New England.

Sulikowski said that it’s not uncommon to find mostly intact seal carcasses bearing bite marks. He has received photos of four or five different seals with bite marks this week. Researchers say such discoveries are not uncommon in Maine and generally only get reported when people are on elevated alert as they are now.

Shark experts say the fatal attack is the result of rebounding great white shark and seal populations along the Maine coast. Gregory Rec/Staff Photographer

Lynda Doughty, executive director of Marine Mammals of Maine, said she regularly sees evidence of interactions between sharks and seals, porpoises and whales, including bite marks and carcasses. And while she hasn’t seen a recent increase in the number of seals found either alive or dead with suspected shark bites, some bite marks have been larger this year.

“It’s so devastating,” Doughty said of the shark attack. “I wouldn’t have thought this would happen in this area.”

Gregory Skomal of the Massachusetts Division of Marine Fisheries, who identified the shark in Monday’s attack as a great white based on a tooth fragment, said the reports of shark bites found on seal carcasses are submitted inconsistently and are of little use when trying to account for the population of white sharks off Maine’s coast.

“People have sharks on the brain,” Skomal said. “It’s hit or miss whether you get those reports.”

Holowach’s death has shaken the community in Harpswell, a rural town on a coastal peninsula with fewer than 5,000 residents and over 200 islands just offshore. Bailey Island is connected by a bridge to the mainland.

“We are stunned and saddened to have lost this lovely woman, who was a well-respected seasonal resident of our community,” the town posted in a statement on Facebook. “We express sincerest thanks to those who provided comfort and support during her rescue and extend our deepest sympathies to her family and friends as they grieve this unimaginable loss.”

In addition to her daughter, Holowach is survived by her husband, Al Holowach, and a son, Dean Holowach, who is a call firefighter with the Westbrook Fire Department.

Several members of the department were at the Holowach family’s home on Bailey Island on Tuesday to help manage the many media members who were there.

“We were up there yesterday providing support for the family,” Westbrook Fire Chief Andrew Turcotte said Wednesday. Turcotte issued a brief statement on the family’s behalf Tuesday, asking the public to respect their privacy “as they mourn the loss of a spouse, mother, grandmother, sister, cousin, and friend to many.”

“While they are very grateful for the outpouring of support that they have received, especially from the island community, they are asking for privacy during this very difficult period of time,” Turcotte said.

Holowach, who also lived in New York City and Naples, Florida, was a recently retired fashion industry executive who had a deep love of Maine and strong ties throughout the state. She was described this week by friends as a vivacious, adventurous and creative woman who looked forward to living here May through October.

After retiring in 2016 as president of Kipling North America, a global luggage and backpack company, she joined the board of directors at Sea Bags, a Portland-based maker and retailer of bags, accessories and home decor.

“Her passion for the ocean, the state of Maine and causes we believe in made her an invaluable supporter and friend,” Don Oakes, CEO of Sea Bags, said in a company statement. “It is with a heavy heart that we share our feeling of loss with Julie’s family.”

An avid swimmer who loved the outdoors, she also was a frequent participant in the Tri for a Cure fundraising triathlon for the Maine Cancer Foundation and an active member of the Harpswell Garden Club.

“She joined the garden club in 2016 and always participated in our activities when she was here,” club president Becky Gallery said. One of the largest garden clubs in Maine, its membership swells to 140 when summer residents return.

Gallery said Holowach would organize carpools and join the club for day trips to various garden venues around Maine, including the Little River Flower Farm in Buxton or Barred Owl Day Lilies in Otisfield.

Garden club members were stunned to learn Tuesday that the victim of the shark attack was one of their own, Gallery said.

“I had no idea she was a former fashion executive,” Gallery said. “She was very down-to-earth and low key. She enjoyed sharing companionship and her love of nature with other gardeners. She was a warm and vibrant person who will be missed by her many friends.”

Staff Writer Edward D. Murphy contributed to this report.