At least nine migrants died and 48 are missing after their boat capsized on Saturday near the Spanish island of El Hierro, rescue services said, in what threatens to be the deadliest such incident in 30 years of such crossings to the Canary Islands, Report informs via Reuters.

The emergency services were able to rescue 27 of 84 migrants who were trying to reach the Spanish coast, they added.

Spanish authorities said the migrants were from Mali, Mauritania and Senegal.

The rescue team received a call shortly after midnight local time from the boat, which was located around four miles east of El Hierro. It sank during the rescue, they said.

“All the migrants on board concentrated in the same side of the boat during the rescue, which made it capsize. Everyone fell into the sea,” said Manuel Barroso, head of Spain’s maritime rescue services.

Wind and poor visibility made the rescue extremely difficult, he added.

Nine bodies have been recovered and the emergency services are still searching for the others.

Three other boats reached the Canary Islands during the night, carrying 208 migrants.

Calm seas and gentle winds associated with late summer in the Atlantic Ocean off Western Africa has prompted a renewed surge of migrants, local authorities said this month.

The route from Africa to the islands, which has a population of around 2.2 million, has seen a 154% surge in migrants this year, with 21,620 migrants crossing in the first seven months, data from the European Union’s border agency Frontex showed.