The 911 call came in around 6 p.m., and within minutes, first responders from Fox Lake, the Illinois Department of Natural Resources, the Lake County Sheriff's Office, and several other neighboring agencies responded.
Officials say the initial reports received indicated that boy, around 15 years old, was swimming in the bay off of a boat in the water and never resurfaced.
Chopper 7 was over the scene, where various emergency vehicles and boats could be seen, at about 7 p.m.
SEE ALSO: Indiana Department of Natural Resources IDs north suburban man who died after Hammond boat crash
For about an hour and a half, divers and search teams conducted what they hoped would be a rescue operation before the search shifted to a recovery operation. Divers entered the water several times.
A drone was also deployed, but crews later switched over to what they called "side-scan sonar," and that is how they were able to find the teenager nearly two hours after he was reported missing.
The teenager's identity has not been released. Officials have not said what may have led to him going underwater.
This is a developing story; check back with ABC7 Chicago for updates.