Updated

Eight Cuban migrants were rescued Monday in the waters off Miami and authorities were searching for five more who remained unaccounted for.

The U.S. Coast Guard received reports of an overturned raft in Biscayne Bay shortly after 10 a.m., Chief Petty Officer Ryan Doss said.

Three people were rescued by a good Samaritan boater. Those initial rescues "reported up to 10 more people in the water," Doss said.

Authorities responding to the scene located five additional migrants by noon. An active search by boat and air continued for the five still believed missing.

Two of the rescued migrants were transported to Mercy Hospital. Their conditions were not immediately known.

"At this point our primary concern is for the welfare and safety of the migrants who are at the hospital and who are being treated at this time," U.S. Border Patrol agent Frank Miller said.

Under the "wet-foot, dry-foot" policy, Cuban migrants who reach U.S. soil are generally allowed to stay, while those caught at sea are returned.

There has been a surge over the last year in the number of Cubans migrants attempting to reach the U.S. by raft.

More than 3,700 Cubans have been intercepted or made it to shore, a 75 percent increase over the previous fiscal year.