Updated

Armed men dressed as police boarded a fishing boat Friday in Curacao and stole about 70 gold bars worth an estimated $11.5 million, police in the southern Caribbean island said.

The boat's captain was struck in the head in the early-morning assault before the thieves made off with the gold in three cars, police spokesman Reggie Huggins said. Authorities believe there were six men involved in the heist. No suspects are in custody.

The captain and three crew members were from the South American country of Guyana, he said.

Huggins declined to say who owned the boat or to provide any details about the possible source of the gold, which weighed approximately 476 pounds.

The boat, by its appearance, would seem an unlikely place to stash that amount of gold. The "Summer Bliss" is a fishing boat with rust streaks on its white cabin and no visible security.

A crew member who gave his name as Raymond Emmanuel told The Associated Press that they left Guyana four days ago and arrived early Friday in Curacao. He said they were delivering the gold to a company in Curacao but said he did not know the name of the business. He referred questions about the source of the gold to the captain, who was meeting with authorities on the Dutch Caribbean island and not immediately available.

Emmanuel said the gold was locked away when the thieves boarded the vessel. "They took everything," he said.

The crew member said neither he nor anyone else on the vessel was armed. "This is normal," he said. "We never carry arms. Since I started working here, I've transported gold once before, and this is the system."

Colin Sparman, executive secretary of the Guyana Gold and Diamond Miners Association, said legal shipments are typically made by air under heavy security. But gold smuggling is common to avoid taxes and royalty payments on the precious metal.

Curacao, just north of Venezuela, is primarily known as tourist destination, particularly for divers. It is also an offshore financial center, especially for people from South America.