|Pirates off the coast of Somalia are continuing their attacks despite international efforts to end the piracy [EPA]
The US military says Somali pirates have shot dead four American hostages on a hijacked yacht in the Arabian Sea as US forces tried to negotiate an end to the hostage drama.
The military said a firefight on Tuesday left two pirates dead and 13 captured.
Among the Americans killed were Jean and Scott Adam, a retired couple active in missionary work who had been sailing the world on the for more than seven years and had planned to take in sites from India to Djibouti to Crete on their latest trip.
Phyllis Macay and Bob Riggle, a couple from Seattle who joined the Adams, were also killed by the band of 19 pirates who commandeered the yacht in waters southeast of Oman, US officials said.
The sequence of events was not immediately clear, but the US military's Central Command said the dead hostages were only discovered after US forces responded to gunfire and boarded the pirated yacht.
"As they responded to the gunfire, reaching and boarding the Quest, the forces discovered all four hostages had been
shot by their captors," the Central Command said in a statement.
"Despite immediate steps to provide life-saving care, all four hostages ultimately died of their wounds."
US warships, which had been closely monitoring the Quest since it emerged three days ago that it had been seized by pirates, approached the vessel after hearing gunfire, the US Central Command said.
It said negotiations to secure the release of the Americans had been under way when the gunfire broke out.
Secretary of State Hillary Clinton said the US "strongly condemns the murder" of the four and urged other nations, particularly in Africa, to contribute to efforts to fight piracy from Somalia.
"This deplorable act firmly underscores the need for continued international progress toward confronting the shared security challenge posed by piracy in the waters off the Horn of Africa," Clinton said in a statement.
Pirate gangs preying on shipping lanes through the Gulf of Aden and the Indian Ocean typically target large merchant
ships, but the snatching of foreigners can also yield high ransoms.