Fourteen people, including at least four children, drowned when the small boat they were traveling on capsized in the Aegean Sea, Greek coast guard officials said on Saturday.

"At least four more were unaccounted (for)," a coast guard official told Reuters.

Previously, The bodies of four children, one man and one woman were recovered off the island of Agathonisi Saturday morning, the coast guard said. Three people — two women and a man — managed to reach the coast and alert authorities to the boat sinking.

The three told authorities they had been in a wooden boat carrying an estimated 21 people which sank, for reasons that were not immediately clear.

The island, known as Eşek Island in Turkish, is located some 20 kilometers west of the Didim district in Turkey's western Aydın province.

A massive search and rescue operation was underway involving three aircraft, Greek navy and coast guard vessels, a vessel from the European border agency Frontex and private boats.

Meanwhile on Saturday, Turkish security forces arrested 41 undocumented migrants and refugees who were attempting to travel to other countries using illegal routes, security sources said.

In the western province of Izmir, Turkish border guards held 18 foreign nationals while they were attempting to cross the Aegean Sea on a fiber boat, said a source, who spoke on condition of anonymity due to restrictions on talking to the media.

Sixteen of the undocumented migrants are Syrian nationals while two others are from Somalia, said the source, adding that women and children were on board.

In northwestern Kirklareli province, gendarmerie forces apprehended 23 undocumented migrants and refugees, said another source.

The foreign nationals, including Afghans, Pakistanis, Iranians and Syrians, were preparing to cross the Turkish border into Bulgaria, according to the source.

Following the legal proceedings, they were sent to the provincial migration authorities.

Turkey has been the main route for migrants trying to cross into Europe, especially since the beginning of the civil war in Syria.