NAIROBI, Kenya (AP) -- Four Americans taken hostage by Somali pirates off East Africa were shot and killed by their captors Monday, the U.S. military said, marking the first time U.S. citizens have been killed in a wave of pirate attacks plaguing the Gulf of Aden and the Indian Ocean for years.
U.S. naval forces, who were trailing the Americans' captured yacht with four warships, quickly boarded the vessel after hearing the gunfire and tried to provide lifesaving care to the Americans, but they died of their wounds, the U.S. Central Command said in a statement.
Two pirates died during the confrontation and 13 were captured and detained, the U.S. Central Command said in a statement from Tampa, Fla. The remains of two other pirates who were already dead for some time were also found. The U.S. military didn't state how those two might have died.
Negotiations had been under way to try to win the release of the two couples on the pirated vessel Quest when the gunfire was heard, the U.S. military said.
The Quest was the home of Jean and Scott Adam, a couple from California who had been sailing around the world since December 2004 with a yacht full of Bibles. The two other Americans on board were Phyllis Macay and Bob Riggle, of Seattle, Washington.
"We express our deepest condolences for the innocent lives callously lost aboard the Quest," said Gen. James N. Mattis, U.S. Central Command Commander.
In total the U.S. said that 19 pirates were involved in the hijacking of the Quest.
Only minutes before the military said the four Americans had died, a Somali pirate told The Associated Press by phone that if the yacht was attacked, "the hostages will be the first to go."
"Some pirates have even suggested rigging the yacht with land mines and explosives so as the whole yacht explodes with the first gunshot," said the pirate, who gave his name as Abdullahi Mohamed, who claimed to be a friend of the pirates holding the four Americans.
Graeme Gibbon-Brooks, the head of Dryad Maritime Intelligence, said he was confounded by the turn of events.
"We have heard threats against the lives of Americans before but it strikes me as being very, very unusual why they would kill hostages outright," he said, adding that the pirates must realize that killing Americans would invite a military response.
The military said U.S. forces have been monitoring the Quest for about three days, since shortly after the pirate attack on Friday. Four Navy warships were involved, including an aircraft carrier.
Last week a Somali pirate was sentenced to 33 years in prison by a New York court for the 2009 hijacking of the Maersk Alabama, a U.S. cargo vessel. That hijacking ended when Navy sharpshooters killed two pirates holding the ship's captain.