Twin Cities grocer Jim Kowalski was standing on the float of a small plane that had just pulled up to the shoreline of a northern Ontario lake, when he lost his balance and fell into the propeller and was killed, authorities said Friday.

Kowalski, 67, the founder of the grocery chain that bears his name, was on a fishing trip in northwestern Ontario at the time of his death with good friend Paul Bruggeman, 50, of Stillwater, the plane's owner and pilot.

Kowalski was standing outside the 39-year-old Cessna A185F Skywagon amphibian plane near the shoreline of Dee Dee Lake, about 20 miles south of the town of Red Lake, according to police.

With the aircraft being brought to shore, Kowalski lost his footing, police and family said.

Kowalski was taken to the Red Lake airport, where he died. Police said an autopsy performed Friday at Lake of the Woods Hospital in Kenora, Ontario, found nothing suspicious about the death.

"These lakes are pretty isolated," said Provincial Constable David Lamme, who is based in Red Lake. "When you are taxiing up to shore, I don't think it would be unusual to be standing on the float, given how slow it was going."

Mike Oase, executive vice president for Kowalski's and Jim Kowalski's nephew, said his uncle had often fished in northern Ontario on fly-ins such as this one and that Bruggeman would join him at times.

"He had been up there several times with the same friend," Oase said. Sometimes they would fly in just for a day, other times stay in a nearby lodge, which was probably the case this time, the nephew added.

Oase said he believed that this was their first venture to Dee Dee Lake. They landed fine on the water's surface and were about to start fishing when Kowalski was fatally injured.

Kowalski, who lived in North Oaks, also owned a plane and had been a pilot for at least the past seven years, Oase said.

Kowalski made Kowalski's Markets into a small upscale chain that has thrived even as the grocery business has become increasingly competitive and dominated by giant national players. The Woodbury-based company tripled in size between the late 1980s and late 2000s.

It began in 1983 with a single store, a former Red Owl, on Grand Avenue in St. Paul.

The stores sport a European market atmosphere and have long been known for high-quality meats, fruits and vegetables.

Jim and wife Mary Anne Kowalski's foundation, Kowalski's 4 Kids, holds an annual golf tournament for charity.

"He liked to fish, though he liked to golf more than he liked to fish," Oase said. "He was a pretty good golfer."

This year's tournament, held last month, raised money for children being treated for substance abuse at Hazelden and for Mary Jo Copeland's Sharing and Caring Hands.

Kowalski was a Hazelden board member and was also a board member of the United Hospital Foundation.