The U.S. Coast Guard says about 20 Cuban migrants are clinging to an iron lighthouse off the Florida Keys.

Chief Petty Officer Ryan Doss says multiple federal agencies will determine whether the lighthouse is dry land under the so-called "wet-foot, dry-foot policy." Cubans reaching U.S. land usually can stay and pursue citizenship.

The 109-foot structure in about 10 feet of water is about 20 miles from Key West. Doss says the migrants swam from their homemade vessel to the lighthouse Friday morning when they saw the Coast Guard approaching.

Ten years ago, U.S. authorities sent home 15 Cubans who landed on an abandoned Keys bridge because they said it did not constitute land. A federal judge later ruled that decision was illegal. Some of the group eventually made it to land in the Keys on another attempt.