The United States Coast Guard airlifted two people from Lake Michigan Tuesday after the pair spent several hours floating in the waters off north suburban Waukegan.

About 4 p.m., a sailor contacted the Coast Guard’s Sector Lake Michigan, saying they had found an personal watercraft floating about 3 miles offshore earlier that afternoon, the Coast Guard said. The unmanned watercraft was found with two cell phones, a set of keys and a wallet with IDs.

After hours of searching, the Coast Guard’s helicopter crews found a man and woman floating in the water, both wearing lifejackets and waving their arms, officials said. The crew deployed a rescue swimmer, then hoisted the survivors into the helicopter.

The man and woman were treated for mild hypothermia, officials said.

Last week, the Coast Guard and the Waukegan Fire Department pulled 15 people from Lake Michigan in two separate incidents. One man, a 50-year-old jet skier, succumbed to his injuries.