ROME (AP) — About 20 migrants are believed to be missing after their boat capsized in the Mediterranean this week, the U.N. refugee agency and the Italian coast guard said Wednesday.

The image made from a video provided by the Italian coast guard shows a patrol boat rescuing migrants from a sinking ship off the coast of Lampedusa, Italy. (Italian Coast Guard via AP)

Seven Syrians were rescued and taken to the southern Italian island of Lampedusa, Italian rescuers said. The coast guard said local officials had spotted the sinking boat around 10 miles (16 kilometers) southwest of the island.

The seven survivors were “in critical condition and many have lost their relatives," Chiara Cardoletti, the UNHCR representative to Italy, said on X.

Survivors said 28 people had left Libya on Sept. 1, the coast guard said in a statement. Twenty-one of them, including three children, "fell into the sea due to adverse weather conditions,” it added. The children were missing.

Naval units and a coast guard aircraft were searching.

The central Mediterranean is one of the world’s deadliest migration routes. According to the U.N. migration agency, more than 2,500 migrants died or went missing attempting the crossing last year, and 1,047 this year.