A man fell through the ice on Lake Erie while riding either an ATV or snowmobile, according to the Monroe County Sheriff's Office.
It happened at about 9:00 p.m. Wednesday near Frenchtown Township, Mich., which is southwest of Amherstburg.
Officials said a search revealed an open area of water almost four metres in diameter where they believed the man fell through.
Neither the man or the vehicle have been recovered.
Police have temporarily suspended the search because of unstable ice and weather conditions.
Anyone with information about the incident is asked to contact the Monroe County Sheriff's Office at (734) 240-7530.