Officials say they recovered the bodies of two females Thursday. Both were wearing life jackets.
The U.S. Coast Guard and other crews have been searching the lake most of the day for the boaters, who went out on Lake Erie Wednesday afternoon.
Crews first located a partially submerged boat Thursday morning near the Davis-Besse nuclear power plant about 30 miles east of Toledo.
The Coast Guard says the four were out on a fishing trip Wednesday but were supposed to return early in the evening.