Authorities in Greece say a woman has died, and several people are believed to be missing after a boat carrying migrants from nearby Turkey sank off the Greek island of Kalymnos.

The coast guard said that 13 people were rescued after the wooden boat sank in mild weather conditions before dawn Friday. A search was launched for the missing migrants.

Greece has seen a spike in arrivals of migrants and refugees in recent months — rising to an average rate of 200 per day, according to the government. Greece says that a 2016 agreement between the European Union and Turkey to combat migrant trafficking is currently not in danger of collapsing, despite a strain in relations between the EU and Ankara.