Phyllis Macay, 59, and her partner Robert Riggle, 67, were sailing with the yacht’s owners Jean and Scott Adam off the coast of Somalia when they were held by pirates on Friday.
Reportedly, negotiations were under way when shooting broke out on board the yacht, Quest.
US military personnel responded by boarding the boat yesterday but found all four had been shot dead by their captors. They attempted first aid but none could be saved.
In the gun battle two of the pirates were killed and 13 others were captured. The remains of two other pirates who were already dead were also found.
An American Navy ship had been shadowing the yacht since Sunday.
Gen James Mattis, the head of the US Central Command, said in a statement: “We express our deepest condolences for the innocent lives callously lost aboard the Quest.”
The boat was seized off the coast of Oman but the pirates then took the vessel to an area between Yemen and northern Somalia.
The Adams, from California, had been sailing around the world since December 2004.
The question now becomes what action US and international forces patrolling the region may be compelled to take against Somali pirates who may be emboldened by radical shifts in governments friendly to the US, such as Yemen.
Regional leaders struggling with internal protests, their attentions are not focused on piracy, give pirates the freedom to act at will in the already dangerous waters off Somalia, Yemen and Oman.
These pirates, already holding hundreds of captured seamen hostage, are making it difficult to sail anywhere in the region, in any size ship, from a small sailing yacht like the Quest, to super-tankers.