CAIRO — A fire broke out Sunday in a detention center for migrants in Yemen’s capital, Sana, killing at least eight people and injuring more than 170 others, scores seriously, the United Nations migration agency said.

The cause of the fire was not immediately clear, according to the International Organization for Migration. More than 90 migrants were in serious condition, and the death toll could climb much higher, according to the Houthi rebels who run the center.

The Houthi, who have controlled the capital since Yemen’s conflict broke out more than six years ago, said that civil defense teams had extinguished the fire and that investigations were underway to determine its cause.

A U.N. official said the fire erupted in a hangar near the main building of the center, which was housing more than 700 migrants. Most had been arrested in the northern province of Sada while trying to cross into Saudi Arabia, she said. The official spoke on condition of anonymity because she was not authorized to brief the news media.

“This is just one of the many dangers that migrants have faced during the past six years of the crisis in Yemen,” said Carmela Godeau, the regional director of the International Organization for Migration.

The narrow waters between the Horn of Africa and Yemen have been a popular migration route despite Yemen’s continuing fighting. Tens of thousands of migrants, desperate to find jobs as housekeepers, servants and construction workers, try to make their way across Yemen every year to the oil-rich Persian Gulf states.

Some 138,000 migrants embarked on the arduous journey from the Horn of Africa to Yemen in 2019, but last year that number decreased drastically, to 37,000, because of the coronavirus pandemic. More than 2,500 migrants reached Yemen from Djibouti in January, according to the migration organization.

Those migrants are vulnerable to abuse by armed trafficking rings, many of them believed to be connected to the armed groups involved in the war. This month at least 20 migrants died after smugglers threw 80 overboard during a voyage from Djibouti in East Africa to Yemen, according to the migration agency.