ATHENS -?Five migrants were confirmed dead and at least 20 others remained missing after a wooden boat carrying dozens of people capsized in waters south of Greece's largest island Crete early Saturday, authorities said.

The tragic incident happened about 15 nautical miles (27 km) south of Kala Limena, a coastal settlement on the southern shore of Crete, according to the Greek coast guard.

Greek national broadcaster ERT reported that the tragedy occurred when one of two commercial vessels dispatched by the national search and rescue center approached the migrants' wooden boat. As passengers attempted to climb a ladder lowered from the ship, many moved simultaneously to one side of the overcrowded vessel, leading to its capsizal.

A cargo ship flying the Panamanian flag rescued 20 people, while vessels from the Hellenic Coast Guard and the European Union's border agency, Frontex, recovered three bodies. Two more bodies were later found at sea.

Survivors told rescuers that about 50 people had been on board, raising fears that the death toll could rise. Search and rescue operations remain underway. Coast guard ships, passing commercial vessels, a helicopter and a military aircraft have been deployed.

Greece, located at the southeastern edge of Europe, remains a major entry point for migrants and refugees attempting to reach the European Union by sea.