At least 18 migrants attempting to cross the Mediterranean Sea in an inflatable boat died when it capsized south of the island of Crete, Greek authorities said Saturday.

The half-sunken boat was located Saturday by a passing Turkish merchant vessel, authorities said.

Two survivors were rescued and a rescue operation to find more was ongoing.

Greece is a major entry point into the European Union for people fleeing conflict and poverty in the Middle East, Africa and Asia and fatal accidents are a common occurrence.

The short but perilous journey from Turkey’s coast to nearby Greek islands in inflatable dinghies or small boats, often in poor conditions, used to be the major route until increased patrols and alleged pushbacks reduced crossing attempts.

In recent months, arrivals from Libya to Crete have surged.

Authorities have not yet determined where the boat came from.

A ship and a plane from European border agency Frontex, a Greek Coast Guard helicopter and three merchant vessels are taking part in the search operation.