Rescue crews have recovered 11 bodies, said Evil Lavilette, mayor of the southwestern town of Pestel, from where the ferry setout for Haiti's capital Port-au-Prince.
"Five children aged two to five died in the accident," Lavilette told reporters.
Police said over 100 people were on board the overloaded ferry, which sank shortly after taking on water about 150 meters from shore. The death toll could increase as dozens are still missing.
Reports from other sources put the number of deaths at 20.
The boat was carrying passengers, food and charcoal on a two-day voyage to Port-au-Prince.
On May 4 last year, a boat carrying immigrants from Haiti to the United States capsized near the Turks and Caicos archipelago, killing 59 people.
