Pirates are asking for a $2m ransom for the release of a captain from the US, who is being held in a lifeboat off the Somali coast.
Captain Richard Philips was captured after a struggle on his cargo ship earlier this week.
He reportedly tried to escape earlier today by jumping into the sea and swimming toward a US warship. However, he was quickly recaptured.
AdvertisementHe was captured by the armed pirates and pulled back into the lifeboat, within view of a US warship.
CNN said that US officials believe Mr Phillips was unhurt in the escape attempt.
Four pirates have been holding Mr Phillips since a foiled bid to hijack his container ship, the 17,000-tonne Maersk Alabama, several hundred miles off Somalia.
Mr Phillips apparently volunteered to get in the lifeboat with the pirates to act as a hostage and secure the safety of his 20 American crew members, who managed to retake control of their ship.
The freighter, which is carrying food aid for Uganda and Somalia, is now on its way to Kenya, its original destination.
The USS Bainbridge is close to the lifeboat and has called on the FBI and other US officials to help negotiate with the pirates.
CNN said two more US warships were on their way to join the destroyer.
Meanwhile, one French hostage and two gunmen were injured when French commandos stormed a yacht held by Somalia pirates.
French forces staged their rescue six days after the yacht, the Tanit, was seized by pirates in the Gulf of Aden and talks broke down, the French presidency said.
One hostage and two pirates were killed and three other adults and a child on the yacht were rescued, a French presidential spokesman said.
'Today, with the threats becoming more and more specific, the pirates refusing the offers made to them and the Tanit heading towards the coast, a operation to free the hostages was decided upon,' the spokesman said.
'During the operation, a hostage was unfortunately killed.
'The four others, including the child, are safe and sound.
'Two pirates were killed; the three others were captured,' said the spokesman.
Earlier, Somali pirates released the Norwegian tanker Bow-Asir and its crew, having held it since 26 March, its owners, Salhus Shipping, said in a statement.