WASHINGTON ( CNN ) -- Pirates in ships are searching for the lifeboat containing four pirates and their hostage -- the captain of a freighter they failed to hijack earlier this week -- according to a U.S. military official with knowledge of the situation . Capt . Richard Phillips of the Maersk Alabama is being held by pirates on a lifeboat off Somalia . The pirates are using ships they have already hijacked and larger ships from which they are launching skiffs , the official said Friday . One of the pirated ships is the German cargo ship Hansa Stavanger , seized April 4 off the coast of Somalia . The U.S. military has been monitoring communications between the pirates , the official said . The guided missile frigate USS Halyburton , with helicopter capabilities , has now joined the guided missile destroyer USS Bainbridge in the area . A third ship , the amphibious assault ship USS Boxer , which has a large medical facility on board , will be there within a day . Richard Phillips , the hostage , tried to escape from the pirates Thursday night by jumping out of the lifeboat , a U.S. official said Friday . Watch what it 's like inside a lifeboat » . Phillips was believed to be trying to swim to the USS Bainbridge , which is in communication with the four gunmen holding Phillips in the 28-foot boat off Somalia 's coast , the official said . Some of the kidnappers jumped into the water , recaptured Phillips , and returned him to the lifeboat , according to the official . Watch what happened when captain tried to escape » . The pirates fired shots , the military official said , but had no further details . A Defense Department official told CNN that Phillips appeared to be tied up by the pirates after the escape attempt . The U.S. official -- who did not want to be named because of the sensitive nature of the situation -- said the escape attempt is being viewed by negotiators as an `` optimistic sign '' that Phillips is in good health . He has been held since Wednesday , when the hijackers seized control of his U.S.-flagged ship , the Maersk Alabama . Watch expert talk about hostage escape attempts » . The captain 's wife Andrea Phillips thanked everyone for their support in a statement . `` My husband is a strong man and we will remain strong for him , '' she said . `` We ask that you do the same. `` Phillips ' 20-man crew regained control of the vessel , and they and the vessel are en route to Mombasa , Kenya , according to the father of one of the crew members . The ship 's owners -- the Norfolk , Virginia-based Maersk company -- would not say how the crew regained control . `` There will be time for due diligence and retrospective review once we have the safe return of all parties and the opportunity for a full debriefing , '' it said in a statement . For the U.S. Navy , the show of strength is more than just a means to resolve a hostage situation , said Chris Lawrence , CNN 's Pentagon correspondent . Attacks in the area have picked up so drastically in recent months that the Navy has to reposition some of its fleet to deal with the threats , he said . iReport.com : How should the U.S. respond ? The pirates have shown no signs of giving in . The Maersk Alabama was on its way to Mombasa , Kenya , with a cargo of food aid when it was attacked Wednesday . It was the first time in recent history that pirates had targeted an American ship . The ship was hijacked some 350 miles off Somalia 's coast , a distance that used to be considered safe for ships navigating in the pirate-infested waters . CNN 's Mike Mount and Barbara Starr contributed to this report .
NEW : Shots fired in escape attempt , captain apparently tied up , military officials say . Pirates using other hijacked ships to look for lifeboat as Navy ships arrive . Captain 's escape attempt viewed as `` optimistic sign '' of his vitality . Richard Phillips , captain of a U.S.-flagged cargo ship , is being held by four gunmen .