A US warship has arrived off the Somali coast where pirates have taken a US ships captain hostage. The US-flagged Maersk Alabama was briefly hijacked by pirates on Wednesday but the crew of 20 Americans managed to retake control of the vessel and are trying to negotiate Captain Richard Phillipss release, second mate Ken Quinn said. Mr Quinn said the four pirates sank their own boat when they boarded the container ship, but the captain managed to talk them into getting off the freighter and into the ships lifeboat with him. The crew then overpowered one of the pirates and sought to exchange him for the captain, Mr Quinn said. "We kept him for 12 hours. We tied him up," he said. The crew eventually released their captive to the other pirates, but the exchange did not work and the captain is still being held by the pirates on the lifeboat.