According to breaking BBC News reports, US defence officials say that four Americans hijacked by Somali pirates off the coast of Oman have been killed by their captors.

The yacht S/V Quest was hijacked on Friday 18 February. It was owned and sailed by Scott and Jean Adam of California (pictured). Before the hijacking the couple had been joined by fellow Americans Phyllis Mackay and Bob Riggle. All four were discovered shot.

In a statement, US Central Command said that negotiations were under way between the US Navy and the pirates, when the US forces heard gunfire coming from the yacht at about 06:00GMT.

They boarded the ship, killing two pirates in the process, and discovered the four Americans shot. The US Navy sailors attempted to provide first aid but the hostages died.

“As they responded to the gunfire, reaching and boarding the Quest, the forces discovered all four hostages had been shot by their captors,” Gen James Mattis of US Central Command Commander explained. “We express our deepest condolences for the innocent lives callously lost aboard the Quest.”

The US Navy captured 13 pirates, and found the remains of two other pirates already dead, the US military said. The US Navy added that it had been closely monitoring the vessel once it learned it had been hijacked, sending four warships to the area.