Seventeen migrants died early Wednesday when their overloaded boat capsized off the Turks and Caicos Islands as it was being towed to port by the authorities.
A spokesman for the British territory's government said that 33 others were pulled from the water after the boat overturned.
All aboard were believed to have been migrants from Haiti.
The sailboat had been detained early Wednesday by the marine division of the Turks and Caicos Royal Police Force and was being towed to the island of Providenciales when it overturned near shore.
Those rescued from the water are now in custody on suspicion of attempting to illegally enter the territory, authorities said.
"I can confirm that 33 people were detained as suspected illegal Haitian immigrants," said Colin Farquhar, of the Royal Turks and Caicos Island Police Force. "This group consisted of 21 males, including one child, and 12 females. These people will be repatriated to Haiti at the earliest opportunity."
He said that the search for casualties had concluded for Wednesday, although a "scaled down search" would begin again on Thursday.
The U.S. Coast Guard deployed two helicopters to the scene after local authorities requested help, U.S. Coast Guard Petty Officer Sabrina Laberbesque said. Two fast-response vessels from Florida Coast Guard bases were also dispatched.
Dozens of Haitians have died in similar accidents in recent years, as many seek to escape an island still reeling from the devastating 2010 earthquake.
In November, at least 30 Haitian migrants drowned when their overloaded boat capsized off the southern Bahamas. Eleven Haitian migrants died in June 2012 when a boat carrying 28 people from the Bahamas to Florida sank.
Turks and Caicos are about 120 miles north of Haiti in the northern Caribbean Sea.