The Burnidge Forest Preserve/Paul Wolff Campground in Elgin is closed as forest preserve police assist another department with a missing person case, officials said Monday morning.
Chopper 7 was over the area Monday afternoon, and there was a large emergency response.
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A dog was also seen with emergency personnel.
Forest preserve officials said the search is for Adam Kurtz, 59, of Gilberts, Illinois.
He left the Timber Trails subdivision about 1 p.m. Sunday on a black Trek mountain bike.
He was last seen wearing a black tank top, dark shorts, a white ball cap and dark tennis shoes.
Anyone with information is asked to call 630-232-8400.
The forest preserve is expected to reopen at sunrise Tuesday.
This is a developing story; check back with ABC7 Chicago for updates.