ATHENS — Greek rescue crews on Monday mounted a search for eight people reported missing after a boat believed to have been carrying migrants capsized off the eastern Aegean island of Samos.

The coast guard said four people had been picked up – two by a fishing boat and another two by a vessel of the European border patrol agency Frontex. The survivors told authorities a total of 12 people had been on board the dinghy when it capsized south of Samos.

Three coast guard vessels, a Frontex boat, a cargo ship and a helicopter were participating in the search, authorities said.

Thousands of people fleeing conflict and poverty in Africa, Asia and the Middle East attempt to enter the European Union through Greece each year. Most make the short but often perilous crossing from the Turkish coast to nearby Greek islands in inflatable dinghies. Others opt to attempt to circumvent Greece in overcrowded sailboats and yachts heading straight to Italy.

Earlier this month, at least 27 people drowned in two separate incidents. In one, 18 people died when a boat that had set sail from Turkey sank off the eastern Aegean island of Lesbos, while in the other, a yacht carrying about 100 people sank in a gale, killing at least nine and leaving six missing.