A 65-year-old Kihei woman died Wednesday after she was apparently bitten by a shark while snorkeling — the third such fatality off south Maui in the past two years, the Maui Fire Department said.

Fire spokesman Edward Taomoto said the woman had upper torso injuries that suggested she was injured by a shark.

Snorkelers found the woman floating face down and unresponsive about 9 a.m., some 200 yards from shore, Taomoto said. She was found near a popular surf spot known as "Dumps" near the Ahihi-Kinau Natural Area Reserve, an area south of Makena State Park.

The snorkelers brought her back to shore, and she died despite firefighters and paramedics giving her lifesaving treatment.

Taomoto said the woman had been snorkeling with two friends, but was alone when she was found.

Firefighters in a helicopter scanned the water after the incident and did not spot the shark, Taomoto said. He said the size and type of shark remain unknown.

Department of Land and Natural Resources spokeswoman Deborah Ward said state officials posted shark warning signs and cleared the water from Big Beach to La Perouse Bay. Officials will reassess the 2-mile stretch before deciding whether to reopen it Thursday afternoon.

Ward said DLNR employees scanned the area on personal watercraft Wednesday, looking for people still in the ocean, and did not report any shark sightings.

Ward said the woman was fatally injured near Kanahena Cove, a popular snorkeling spot inside a marine reserve.

Tiger sharks have been frequently detected off south Maui in preliminary data from a University of Hawaii study.

The two-year study was launched in 2013 following a cluster of shark-bite incidents around Maui in 2012 and 2013. The scientists leading the study were not available to comment Wednesday.

Data from the study that were released in November showed tiger sharks that had been tagged for the study were most frequently detected in coastal shelf habitats less than 600 feet deep — areas that are more common around Maui than around other Hawaiian Islands.

Carl Meyer, one of the study’s lead scientists, said in November that the sharks preferred the same depths around Oahu, but that the most frequented sites don’t line up with popular swimming and surfing sites on Oahu to the extent they do on Maui.

Wednesday’s incident marks this year’s first fatal shark attack in Hawaii and the third in two years in waters off Makena.

» On Aug. 14, 2013, a shark bit 20-year-old visitor Jana Lutteropp, off Keawakapu Beach, severing her right arm. She died from her injuries a week later.

» On Dec. 2, 2013, Patrick A. Briney, 57, of Stevenson, Wash., was kayak fishing off Makena Landing when he was bitten on the right leg. He died from severe bleeding.

According to state data, there have been 91 shark incidents in the islands in the past 20 years: 43 for Maui, 18 for Oahu, 15 for Hawaii island, 12 for Kauai, two for Lanai and one for Molokai.