At least 78 migrants are dead after a fishing vessel capsized and sank off the southern coast of Greece, authorities said Wednesday. A rescue operation saved 104 others so far after the boat went down around 50 miles southwest of Pylos, reportedly during a journey from Libya to Italy. It’s not clear how many people were on board at the time of the disaster, or how many more may be missing at sea—authorities fear it may be dozens more. Greece’s coast guard said the rescue operation had been hampered by powerful winds and alleged that passengers weren’t wearing life vests and “refused any help.” Four of the people saved were taken to the hospital with hypothermia symptoms, the coast guard added.