The US Coastguard in Miami, which spends much of its time intercepting would-be Haitian immigrants trying to reach the United States on rickety boats, said as many as 800 people were thought to have been crammed aboard the ferry. The Coastguard, which sent a helicopter to aid local rescue workers, estimated that at least half of those on board had drowned.
Thousands of Haitians wailed in grief on the pebbled beach of the fishing village of Montrouis as UN divers and a half-dozen fishing boats searched 200 yards offshore for victims. US Coastguard and UN helicopters hovered above the spot where the ferry, the Pride of Gonave, had disappeared in 75ft of water.
"The boat was overloaded. When it manoeuvred to disembark [passengers], everybody ran to one side and the boat tipped over," said survivor Benjamin Joseph, 38, a civil engineer. "If I'm alive, it was a miracle."
The ferry was, in fact, a 60ft wooden sailing sloop with an outboard motor, carrying food from Montrouis to the island of La Gonave to return with vital charcoal used for heating and cooking by Haiti's six million inhabitants. La Gonave residents, workers or farmers pack themselves on to such boats along with livestock to seek work or earn a living in the Western hemisphere's poorest nation.
The vessel was certified to carry only 80 passengers, according to Lt Steve Banks, of the US Coastguard. Its captain told police he had 250 passengers. The captain was in custody while police investigated. His name was not released.
Survivors claimed that many passengers were locked inside the ferry, which consisted of two enclosed decks and a third deck that opened on to the vessel's stern.
As it reached Montrouis at dawn, it turned around so passengers could transfer to rowboats to go ashore. Passengers rushed to one side of the ship, causing it to capsize, survivors said.
Owing to overcrowding, ferry disasters are common off Haiti, a French- speaking republic which shares the island of Hispaniola with the Spanish-language Dominican Republic.
The largest ferries have an official capacity of 300 people - a limit often ignored by Haiti's underregulated sea transport industry. The government claims it doesn't have the resources to monitor the vessels.
The worst disaster was in February 1993 when the ferry Neptune sank about 50 miles west of Port-au-Prince with up to 1,500 people on board. The death toll was put at between 500 and 700. Two years ago 100 drowned in another incident.