Search was underway Saturday for five people who were believed to be missing after a boat with approximately 50 undocumented migrants sank off the Lesvos island in the eastern Aegean Sea, according to the Greek Coast Guard.

The search was launched after an unidentified person made a telephone call to authorities that he was aboard a vessel carrying about 50 people which was in need of help.

Three speedboats rushed to the area. The vessel has not been located yet, but 45 immigrants were found on a nearby beach in good condition, Coast Guard officials said.