ATHENS, Greece — Another body was recovered Tuesday from the sea off the southern Greek island of Crete after a migrant smuggling boat sank in rough weather, bringing the death toll to four, including two children. Fifty-seven people were rescued. 

A major search and rescue operation was underway as the survivors were unable to say how many people had been on board when the small yacht sank late Monday and whether anyone still was missing. 

Two women and two boys, ages 6 and 7, died in the shipwreck, Greece's coast guard said. The bodies of the children and one woman were recovered on Monday night. 

Authorities were alerted after a person claiming to be a passenger on the sinking boat called an emergency number. The boat went down 12 nautical miles (22 kilometers) east of Crete in rough seas, the coast guard said. 

Two coast guard vessels, two aircraft and five ships that had been sailing nearby were participating in the search. The coast guard said survivors were not able to give an account of how many people had been on board initially, and it was unclear whether there were any missing.

Greece is one of the main entry points into the European Union for asylum-seekers and migrants from the Middle East, Asia and Africa. The vast majority cross from the Turkish coast to nearby Greek islands in dinghies. 

Authorities say they have seen an increase in smuggling gangs using larger boats, such as yachts and sailing boats, to pass south of Crete and head to Italy.