MADISON, Wis. -- An ice boater has died after falling through the ice on Lake Monona on Tuesday afternoon.

The Madison Fire Department Lake Rescue Team received a report shortly before 4 p.m. Tuesday of a person in the water near the Tonyawatha Boat Launch in the city of Monona. Callers reported seeing an ice boat sail sticking out of the water.

Dane County Sheriff's Department said it was determined the victim had been ice sailing and went through the thin ice into open water.

Madison Fire Department spokesman Eric Dahl said that team members used cold water rescue suits and ice sleds to cross the thin ice.

Dane County Sheriff Dave Mahoney said the man's body was found in the water and his hands were clinging to the ice.

By the time a rescue sled reached the man, he had spent at least 30 minutes in the frozen water.

David Platt, who lives on the lake, spotted the boat after it crashed through the ice and videotaped the rescue effort.

"It froze over about two days ago, so I was thinking, 'There's no way he should have been out there,'" Platt said. "He was in the water. It must have been just his head I was looking at."

Platt said he feared the worst as he watched rescue crews working to resuscitate the man.

"I was thinking he didn't make it. I was very concerned he didn't make it," Platt said. "When they got him on the sled out there, they started CPR on him and worked on him for quite a while, and then brought him in and started CPR when they got here."

Lilly Bickers, who also lives on the lake, said she watches ice boaters from her home. She said she wonders why anyone would test the icy waters so early in the season.

"It's a pretty exciting sport, but I think you have to wait until the ice gets a little thicker," Bickers said. "The ice boats you need quite a bit of wind across the way, so with the lack of wind and the heaviness of the boat, I can't imagine it being pretty safe out there."

The man was transported to UW Hospital, where resuscitation efforts continued. Sgt. Kerry Porter, of Dane County Sheriff's Department, said the man was pronounced dead at the hospital at 5:44 p.m. Tuesday.

The victim was identified as William H. Gedko, 63, of Madison.

The coroner said an autopsy revealed that Gedko's death was due to natural causes and not related to being in the water for an extended period of time.

Mahoney warned others to stay off the ice. He said that just because one area is thick enough, it doesn't mean it will be safe everywhere.

"Stay off the ice, particularly as we move into the Christmas holiday, where weather is predicted to be rain, which will make our ice even more treacherous than it is today," Mahoney said.

Mahoney said Tuesday that he feels the ice isn't safe enough in most places to even support a person's weight, much less any type of boat or vehicle.

Stay tuned to WISC-TV and Channel 3000 for continuing coverage.