Greece’s coast guard said it retrieved the bodies of 12 migrants from a boat near the island of Crete early on Monday, 18 Aban. The cause of their deaths is not yet known.

According to Reuters, 18 other people from the same boat were rescued about 15 nautical miles from the port of Kaly Limenas.

A coast guard official said dozens of other people were also rescued in two separate incidents in the waters around Crete, and all those rescued will be taken ashore.

Greece is one of the main entry routes for migrants and refugees from the Middle East, Africa and Asia to Europe. During the migration crisis of 2015 and 2016, nearly one million people, mostly from Turkey, entered the country’s islands.

Despite a reduction in total arrivals and the strengthening of border patrols, sea arrivals of migrants from north-east Libya to Crete have increased.