Chicago (CBS) — A 16-year-old boy was rescued from the water and another boy is still missing from Lake Michigan off the coast of Waukegan, officials say.

Just after 4:30 p.m. Friday, the Waukegan Fire Department responded to a call for a person who had slipped off a pier into Lake Michigan at Waukegan Municipal Beach and another person who had jumped into the water to rescue the first.

The teenager who originally fell in made it out of the water and was transported to Vista East Medical Center in Waukegan. His condition is unknown at this time.

After about an hour and a half of searching the water, rescue divers were unable to locate the second teen. The operation was switched to involve sonar technicians.

Divers are rescuers are waiting for the harsh weather conditions to move out of the area, so they can resume searching for the boy.