One man is dead after a boat capsized in Lake Superior Monday.

The St. Louis County Sheriff's Office said Duluth firefighters found Donald James Sarter, 68, of Sturgeon Bay, Wis., in shallow water off Park Point near Sky Harbor Airport. Despite lifesaving efforts at the scene, Sarter was pronounced dead.

Sarter was the operator of a 21-foot Monark aluminum-hulled boat that capsized about 11 a.m. after the engine became waterlogged, according to the Sheriff's Office report. His passengers, Donald Alan Slater, 59, of Sault Ste. Marie, Mich., and Randall Joseph Corsten, 50, of New Franken, Wis., were able to swim to the nearest shore, where they called 911 to report Sarter was missing.

The other two men were taken to a hospital by a private party, according to a news release from the city of Duluth. The Sheriff's Office said they had no apparent injuries.

According to the Sheriff's Office, one of the men told deputies that all three had been wearing life jackets, but they were not zipped together in front.

The big waves persisted throughout the rescue operation.

"We saw the rescue boats barreling out and around," Karen Wilson, of Salem, Ore., said, describing rescue vessels carrying through the Superior Bay side and out into the lake through the Superior Entry. Wilson was in town with her husband, Doug. They'd once lived in Duluth and were visiting, Doug with his binoculars trained on the rescue far down the beach.

"They're searching for someone over there," he said as multiple vessels conducted their search.

The Duluth Fire Department issued a red-flag warning for Park Point beaches, warning people to stay out of the water due to a high risk of rip currents. The warning was in effect until 10 a.m. on Tuesday.

The Duluth police and fire departments, Superior police and fire departments, St. Louis County Sheriff's Office and Rescue Squad and the U.S. Coast Guard all participated in the rescue effort, staging at the Sky Harbor Airport, near the end of Park Point.

The city of Duluth also said "would like to acknowledge Northland Constructors and Wren Works LLC for their assistance with the call." Crews from both were working nearby on the airport's runway realignment project.

The boat is owned by Roen Salvage of Sturgeon Bay, Wis., which employed all three men.

According to the company's website, Sarter was hired as a deckhand by Roen Steamship Co. in 1971 and moved to Roen Salvage Co. two years later. He had worked on more than 100 marine construction projects and was currently the company's head superintendent.

The company, which formed in 1949, has been involved in numerous projects in the Twin Ports.

The St. Louis County Sheriff's Office is investigating the incident.