MADRID (AP) — About 50 migrants were missing after their boat overturned some 100 kilometers (60 miles) south of Spain’s Canary Island of El Hierro in the Atlantic Ocean, Spanish media reported Monday.

The national marine rescue service said one of its helicopters rescued nine people who were found clinging to the boat Monday morning following a warning call from a merchant vessel in the area.

State news agency Efe said that once transferred to El Hierro airport, the rescued migrants reported that 60 of them had set sail nine days ago and that the open-topped wooden boat ran into problems Saturday.

The rescue service was unable to say how many people may have been on the boat and no one was available to comment at Civil Guard police offices in the Canary Island capital of Santa Cruz de Tenerife.

Efe said the migrants were of sub-Saharan origin. There were no details on which country they had sailed from.