Mexico City ? At least 20 Haitian migrants died and 58 were missing Friday after an overloaded sailboat capsized off the Turks and Caicos Islands.

A U.S. Coast Guard cutter, accompanied by a helicopter and a C-130 plane, searched for survivors of the tragedy, which is part of a dramatic upswing in illegal migration from the poorest country in the Western Hemisphere.

The 30-foot sailboat that capsized Friday was being towed to shore by a Turks and Caicos police boat when it flipped, tossing passengers into the sea, the Coast Guard said. The Associated Press reported that Turks and Caicos officials denied the sailboat was being towed when it capsized shortly after 4 a.m. a mile south of Providenciales island in the Atlantic Ocean.

Some of the recovered bodies were missing limbs, apparently from shark attacks. At least 63 passengers were rescued.

Coast Guard spokesman Dana Warr said that the sailboat, believed to be carrying 150 people, was dangerously overloaded and that there was no indication the police towboat was responsible for the incident.

“It would be difficult to assume responsibility on their part with 150 people on a boat that size,” Warr said. “I don’t think anybody on those boats is safe. There are no safety parameters by the Haitian government.”

Haitians are typically sent back to their country after being taken into U.S. custody at sea or on land. The policy has been vigorously protested by Haitian activists who say their fellow citizens should be afforded the same treatment as Cubans, who are generally granted asylum if they reach U.S. soil under the “wet foot, dry foot” policy implemented during the Clinton administration.