WASHINGTON: Four Americans and two Somali pirates were killed Tuesday during an attempt to free the US hostages from their yacht seized on the Indian Ocean, the US military said.

US forces, which have been closely monitoring the S/V Quest since it was known to be pirated three days ago, approached the vessel after hearing gunfire, the US Central Command said.

After boarding the yacht, “the forces discovered all four hostages had been shot by their captors. Despite immediate steps to provide life-saving care, all four hostages ultimately died of their wounds,” a statement said.

“We express our deepest condolences for the innocent lives callously lost aboard the Quest,” said General James N. Mattis, the head of US Central Command.

The S/V Quest's owners, retired couple Jean and Scott Adam, had been sailing around the world for more than seven years and planned to take sites from India to Djibouti to Crete on their latest trip.