More than 60 migrants are believed to have died after a boat carrying them from Senegal capsized in the Atlantic Ocean off Cape Verde, the authorities said this week.

The boat capsized at some point after leaving Senegal on July 10, the Reuters news agency reported on Wednesday, citing the Senegalese Foreign Ministry.

A Spanish fisherman found the boat floating about 150 miles north of Cape Verde’s Salt Island, the country’s national police said on Monday. The islands of Cape Verde lie several hundred miles west of Senegal.

Thirty-eight people survived the accident, including four children, Safa Msehli, a spokeswoman for the United Nations migration agency, said in a brief email on Thursday. She said seven people had been confirmed dead and 56 others were still missing.

“Sadly, people missing at sea are presumed dead,” Ms. Msehli said, adding that all but one of the 101 people on board were from Senegal.

No other details about the tragedy, including the boat’s original destination, could be confirmed on Thursday morning. The Senegalese authorities could not be reached for comment overnight, and the Cape Verde national police did not immediately respond to a request for comment.

Smugglers have been piling migrants into poorly constructed or overcrowded boats to make the crossing to Europe from their home countries in sub-Saharan Africa and elsewhere. Many of the migrants take immense risks in order to escape war and poverty at home.

Dozens of migrants drowned after a rickety boat carrying them to Italy from Tunisia capsized in the Strait of Sicily last week.