At least 11 people were confirmed dead while 31 others were rescued Thursday after a boat loaded with suspected migrants capsized north of an uninhabited island near Puerto Rico, the U.S. Coast Guard said.

It wasn't immediately clear how many people were aboard the boat when it turned over, said U.S. Coast Guard spokesperson Ricardo Castrodad. He said a "mass rescue effort" was still underway.

"We're looking to rescue as many people as we can and find as many survivors as we can," he said.

At least eight Haitians were taken to the hospital, although the nationalities of all those aboard the boat were not immediately known.

The incident is the latest in a string of capsizings across the region as migrants from Haiti and the Dominican Republic flee violence and poverty in their countries. A U.S. Customs and Border Protection helicopter spotted the overturned boat late Thursday morning.

"If not for that, we would not have known about this until someone would have found any sign or received reports from people that their loved ones are missing," Castrodad said. "They found them early enough that we were able to coordinate a response."

The boat was spotted more than 11 miles (18 kilometers) north of the uninhabited island of Desecheo, which is off Puerto Rico's west coast. The U.S. Coast Guard said those rescued were 20 men and 11 women.

From October 2021 to March, 571 Haitians and 252 people from the Dominican Republic were detained in waters around Puerto Rico and the U.S. Virgin Islands, according to U.S. Customs and Border Protection. The majority of those Haitians, 348 of them, landed in Puerto Rico's uninhabited Mona Island and were rescued.

Many have criticized the administration of U.S. President Joe Biden for deporting more than 20,000 Haitians in recent months given the country's deepening turmoil.

Meanwhile, the U.S. Coast Guard said that in the fiscal year that ended Sept. 30, it apprehended 1,527 Haitians, 838 Cubans and 742 people from the Dominican Republic in the region, which includes Florida and the Caribbean.

Since then, trips of human smuggling boats have only increased, authorities say.

Haiti is struggling with a surge in gang-related violence that has killed dozens of people, including women and children, and caused thousands of families to flee their homes. Kidnappings also have spiked, including those of eight Turkish citizens who on Sunday were forced off a bus they had boarded in the Dominican Republic.