At least 15 people, including five children, drowned on Saturday after a boat carrying refugees and migrants from Turkey to Greece sank off the coast of Agathonissi island in the Aegean Sea, the Greek Coast Guard said.

About 20 people were believed to have been on board and several are unaccounted for. Coast Guard vessels and helicopters were searching for more survivors off the island of Agathonissi, close to the Turkish coast, the BBC reported.

Saturday’s tragedy is the first such case in several months in the Aegean. Hundreds of refugees and migrants have perished in the Aegean Sea since 2015.

The number of new arrivals decreased dramatically in recent months to a few dozen per day, according to Greek Coast Guard figures.