Twenty-one people are missing after a boat sank in the Caribbean Sea off the shore of Venezuela, officials said Thursday.

Lt. Kerron Valere of the Trinidad and Tobago Coast Guard said Thursday that four passengers have been rescued. The small craft named "Yonaily Jose" left Venezuela a day earlier and overturned in rough seas.

Valere says Venezuela is leading the search for the missing within that nation's waters, and the Trinidad and Tobago Coast Guard is assisting.

Venezuelan officials say that most of the passengers were women, and the boat overturned near the island of Patos, roughly 5 miles (8 kilometers) from land.

Officials had initially reported that the boat was carrying 35 passengers.

Local outlet Noticiero Digital said that 35 people were aboard the ship and at least eight people had been rescued. It cited officials from the navy of Trinidad and Tobago and said the boat had left the port of Las Salinas in the Venezuelan state of Sucre on April 23.

It reported that 22 of the migrants were women and the boat's captain, Francisco Martínez, was among those rescued.

In recent years, an estimated 3.7 million Venezuelans have fled the crisis-wracked country where a political struggle is now playing out between elected President Nicolas Maduro and U.S.-backed opposition lawmaker Juan Guaido, who declared himself the interim leader in January.

Most of Venezuela's migrants travel by land into neighboring Colombia and Brazil, but others overload fishing boats to cross the sometimes deadly Caribbean waters and head for nearby islands.

In January 2018, authorities called off a search for more than two dozen migrants who boarded a boat leaving Venezuela that crashed onto rocks on the nearby Dutch island of Curacao. Officials said two people survived that crash.