At least two people have died and 186 others are missing after four boats carrying migrants from Africa capsized overnight in waters off Yemen and Djibouti, the U.N.’s migration agency said on Friday.

Two vessels capsized off Yemen late Thursday, said Tamim Eleian, a spokesperson for the International Organization for Migration, or IOM. Two crewmembers were rescued, but 181 migrants and five Yemeni crewmembers remain missing, he told The Associated Press.

Immigrants are taken by smugglers on overcrowded boats across the Red Sea. (Photo by Tahsin Ceylan/Anadolu via Getty Images)

Yemen is a major route for migrants from East Africa and the Horn of Africa trying to reach Gulf countries for work, with hundreds of thousands attempting the route each year. To reach Yemen, migrants are taken by smugglers on often dangerous, overcrowded boats across the Red Sea or Gulf of Aden.

The numbers making it to Yemen reached 97,200 in 2023 — triple the number in 2021. Last year, the number dropped to just under 61,000, probably because of greater patrolling of the waters, according to an IOM report this month.

Over the past decade, at least 2,082 migrants have disappeared along the route, including 693 known to have drowned, according to the IOM. Some 380,000 migrants are currently in Yemen.