LAKE DELTON, Wis. >> Authorities said Sunday that an ice resurfacing machine caused a suspected carbon monoxide leak that sent dozens of people to hospitals after a junior hockey game at a Wisconsin rink.

At least 81 people were treated for symptoms of carbon monoxide poisoning after the leak was discovered Saturday at Poppy Waterman Ice Rink in Lake Delton.

Delton fire Chief Darren Jorgenson told the Star Tribune of Minneapolis the carbon monoxide came from one of the rink’s two propane-fueled resurfacing machines. Jorgenson said the machine "wasn’t fully combusting the propane," and the ventilation system was unable to offset the problem.

The employee operating the machine thought it was functioning properly, Jorgenson said. Both machines, which the fire chief said passed inspection just before the hockey season began this fall, will be inspected Monday.

While the rink is not required by law to have a carbon monoxide detector in the building, Jorgenson said such detectors are a good idea in public buildings.

Players reported having headaches, dizziness and nausea after a game between the Dells Ducks and the Rochester, Minn., Ice Hawks, the Delton Fire Department said. One person was still receiving treatment Sunday, while a Ducks player was getting oxygen therapy at a hyperbaric chamber in Milwaukee, the Minnesota Junior Hockey League said.