The body of a Grayslake Central High School student was pulled from the water of Third Lake Monday evening, authorities said.
Lake County sheriff's police and friends identified the victim as Matt Reed, an incoming junior.
Reed had been on a pontoon boat Monday afternoon with six friends when they went into the water for a swim, authorities said.
Reed struggled while in the water, went under and never resurfaced, according to Grayslake Fire Protection District Chief John Christian.
Someone who had been on the boat called 911 from a cellphone and authorities responded with a sonar team and divers. Reed's body was found in about 60 feet of water, about 200 feet from the lake's eastern shore, Christian said.
A small group of Reed's friends were among those who gathered at the shore Monday evening. News of the accident spread via text messages.
A friend of Reed's family, Hayden Brown of Grayslake, said he was in disbelief when he heard about the accident. He described Reed as a "very funny guy" who was caring and loved basketball.
Brown called the teen a "very ferocious competitor."
Emergency crews were dispatched to the lake just north of the College of Lake County after 4 p.m. The search launched from the east side of Third Lake in the Mariners Cove subdivision. Crews set up a staging area on the west side of the lake.
Rescuers began using sonar equipment on the east side of the lake about 6:30 p.m. in hopes of speeding up the search effort, Christian said.
At that time, authorities confirmed crews were conducting a recovery operation, not a rescue. About 7 p.m., they discovered the body and pulled it from the water.
The body of water, one of two lakes within the village of Third Lake, is a private lake that's gated and locked. Mariners Cove residents are issued keys to access the water, resident Jeanne Hendrickson said.
Hendrickson was preparing dinner at her home on Mainsail Drive when a neighbor came to the front door to make sure she and her family were OK. Hendrickson spent the next few hours beneath a tree on her front lawn, watching police and fire activity.
She said firefighters train at Third Lake on a regular basis, "so it's not unusual to see all these vehicles here. But when they come in for training they don't have their lights on."
Neither police nor fire officials could recall another fatality on the lake.
Lake County Undersheriff Raymond J. Rose said his office is investigating the accident. Police interviewed people who were on the pontoon boat with Reed, Rose said.
Grayslake fire district personnel were assisted on scene by Antioch, Countryside, Gurnee, Fox Lake, Lake Villa, Libertyville and Wauconda fire department crews.
• Daily Herald staff writer Christopher Placek contributed to this report.