HIGHLAND PARK, Ill. — Authorities say a 46-year-old man has died and a 52-year-old woman is missing after going swimming in hazardous waters in Lake Michigan near a Chicago suburb.

The city of Highland Park says in a statement the Elgin woman and the Itasca man were part of a group of about 10 people in a "cold weather swim group" that went in the lake Sunday morning at Park Avenue Beach amid huge waves and gale-force winds.

An autopsy performed Monday revealed that Stanislaw Wlosek Jr. drowned. A witness says some men tried unsuccessfully to throw the woman a line .

A Coast Guard helicopter from Traverse City, Michigan, searched the area Sunday. Police in Illinois and Wisconsin are watching for the missing swimmer.