The Chicago Fire Department responded to DuSable Lake Shore Drive and Randolph Street in the Loop around 12:45 p.m. for a report of a person who went missing.
Parents told ABC7 their 20-year-old son was onboard the same boat as the person who disappeared.
ABC7 was told a group of college students home for their fall break were on that boat.
One person apparently jumped off of the boat while it was moving, and that is when they went missing.
CFD searched the water near DuSable Harbor with divers and a helicopter.
The search has been turned over to the U.S. Coast Guard and Chicago police. It is now a recovery mission, officials said.
Authorities did not immediately provide further information.