Duluth Fire Marshal investigators on Thursday were checking out what caused an apparent carbon monoxide leak that left several hockey players, coaches and the Zamboni driver sick at the city's Fryberger Arena. A parent in the stands noticed people complaining of nausea and headaches and called the Fire Marshal. Thirty people were evacuated.

The Duluth News Tribune reports that carbon monoxide levels were detected at five times the normal rate.  The Northland News Center says the propane-powered Zamboni machine and the arena's aging heating and water systems might have all been factors. (Photo courtesy of Northland News)

No word yet on the condition of the people who went to the hospital or when the arena will be safe. Calls to Fryberger went unanswered Thursday afternoon.