"We're trying to determine how many souls were on board and what is the status of those souls," said Lieutenant John Schofield, a navy spokesman.

A Colombian navy source in Bogota said the helicopter was carrying between three and five US military personnel and had flown from a US warship when it crashed.

The navy said a search and rescue effort was launched immediately after the SH-60B crashed.

"The helicopter was conducting scheduled flight operations when it crashed in international waters west of Colombia," it said in a statement.

The helicopter was from an anti-submarine squadron based in Mayport, Florida, the navy said.

In Bogota, the Colombian navy source said the helicopter crashed about 280 nautical miles (500 kilometers) from the Colombian port of Buenaventura.

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