At least 15 people have died as two boats carrying migrants sank in Greek waters late Wednesday, and rescuers were looking for dozens still missing, authorities said early Thursday.

The coast guard said 15 bodies had been recovered near the eastern island of Lesbos after a dinghy carrying about 40 people sank. Five people were rescued and three had been located on a rocky outcrop near the site of the sinking.

A second rescue effort was launched several hundred kilometers (miles) to the west, near the island of Kythira, where a sailboat carrying about 100 migrants hit rocks and sank late Wednesday.

Officials said 30 people had been rescued after that boat hit rocks off the village port of Diakofti on the east of the island. Winds in the area were up to 70 kph (45 mph).

“We could see the boat smashing against the rocks and people climbing up those rocks to try and save themselves. It was an unbelievable sight,” Martha Stathaki, a local resident told The Associated Press. “All the residents here went down to the harbor to try and help.”

Fire service rescuers lowered ropes to help migrants climb up cliffs on the seafront. Local officials said a school in the area would be opened to provide shelter for the rescued. Navy divers were also expected to arrive Thursday.

Most migrants reaching Greece travel from neighboring Turkey, but smugglers have changed routes in recent months in an effort to avoid heavily patrolled waters around Greek islands near the Turkish coastline.

Kythira is some 400 kilometers (250 miles) west of Turkey and on a route often used by smugglers to bypass Greece and head directly to Italy.