The Aegean Wind was carrying more than 37,000 tons of iron ore from Brazil to Houston when a blaze broke out in the mess hall before dawn local time, according to the vessel's owner, Piraeus-based Atlantic Bulk Carrier Management Ltd.
The ship was about 100 miles (160 kilometers) north of Venezuela at the time, and about 34 miles (55 kilometers) from Margarita Island.
Venezuelan navy Adm. Carlos Maximo Aniasi Turchio said that nine crew members who had been unaccounted for were dead. Six were from the Philippines and the other three were from Greece, he said.
"We don't know if they died from asphyxiation or burns, but the (ship's) commander has confirmed to us that they did die," Aniasi Turchio told Venezuelan state television.
He said that five injured crew members were taken by helicopter to Margarita Island and were to be transferred later to a military hospital in the capital, Caracas.
One was in "delicate condition" from severe burns, Aniasi Turchio told the state-run Venezolana de Television.
Aniasi Turchio said the fire had been extinguished and 10 crew members, including the captain, were to be evacuated shortly.
Atlantic Bulk Carrier Management spokeswoman Elise Goonen said the crew members were in the mess hall when the fire started.
"We have no news of them yet," Goonen told The Associated Press before Aniasi Turchio announced that the nine were dead.
Rafael Lugo, commander of Venezuela's maritime support and rescue agency, told Telesur news network that a group of rescuers with oxygen tanks would be sent to search for the missing.
Lugo also said the fire began in the engine room and spread to the cabins.
It was not immediately possible to reconcile the conflicting information on where the fire broke out, and its cause was not known.
The Aegean Wind has a 24-member crew made up of 15 Filipinos and nine Greeks.