NAIROBI, Kenya — The American crew of a hijacked U.S.-flagged ship retook control of the vessel from Somalian pirates Wednesday but the captain was still being held hostage in a lifeboat, according to at least three people on board.

A spokesman for the ship company Maersk, Kevin Speers, tells AP Radio that the destroyer USS Bainbridge is on the scene.

He adds that the boat with the pirates is floating near the Maersk Alabama.

The Bainbridge was among several U.S. ships, including the cruiser USS Gettysburg, that are patrolling in the region.

"Right now they want to hold our captain for ransom, and we are trying to get him back," second mate Ken Quinn told CNN in a live interview after the cable news network called the boat.

"We had one of their hostages, we had a pirate. We took him for 12 hours. We tied him up. We returned him. But they didn't return the captain," Quinn said.

The captain was on a lifeboat with the pirates, Quinn said.

"Right now we are trying to offer them whatever we can, food. It's not working too good," Quinn said.

He said the crew was communicating with the captain by radio.

The company that operates the ship confirmed that it was back in the crew's hands and said the hijackers had departed with a crew member.

Capt. Joseph Murphy, an instructor at the Massachusetts Maritime Academy, told The Associated Press that he was called by the Department of Defence and told the crew, including his son Shane, the second in command, had control of the ship.

Murphy's wife, Serena Murphy, of Seekonk, Massachusetts, told the AP her husband said by phone that he was OK, but that pirates had taken the captain off the ship and he was now in charge.

Colin Wright, who identified himself as a third mate aboard the ship, told the AP that, "Somalian pirates have one of our crew members in our lifeboat and we are trying to recover that crew member."

Asked whether that crew member was the ship's captain, Collin told the AP he couldn't say anything else. A person aboard the ship told the AP by phone earlier that it was the captain who was being held by the pirates.

At one point, the pirates had held the boat and the entire crew of Americans. Wright said: "We're really busy right now, but you can call back in an hour or two."

U.S. President Barack Obama was following the situation closely, foreign policy adviser Denis McDonough said.

Andrea Phillips, the wife of Capt. Richard Phillips of Underhill, Vermont, said her husband has sailed in the waters off Somalia "for quite some time" and a hijacking was perhaps "inevitable."

The ship was carrying emergency food relief to Mombasa, Kenya, when it was hijacked, the Copenhagen-based container shipping group A.P. Moller-Maersk said.

"We are able to confirm that the crew of the Maersk Alabama has is now in control of the ship," said Kevin Speers, a spokesman for Maersk Lines Limited. "The armed hijackers who boarded this ship earlier today have departed, however they are currently holding one member of the ship's crew as a hostage. The other members of the crew are safe and no injuries have been reported."

It was the sixth vessel seized within a week, a rise that analysts attribute to a new strategy by Somali pirates who are operating far from the warships patrolling the Gulf of Aden.

Cmdr. Jane Campbell, a spokeswoman for the U.S. Navy's Bahrain-based 5th Fleet, said that it was the first pirate attack "involving U.S. nationals and a U.S.-flagged vessel in recent memory." She did not give an exact timeframe.

Joseph Murphy, a professor at the Massachusetts Maritime Academy, said his son was a 2001 graduate who recently talked to a class about the dangers of piracy.

Somali pirates are trained fighters who frequently dress in military fatigues and use speedboats equipped with satellite phones and GPS equipment. They are typically armed with automatic weapons, anti-tank rocket launchers and various types of grenades. Far out to sea, their speedboats operate from larger mother ships.

The U.S. navy said that the ship was hijacked early Wednesday about 450 kilometres southeast of Eyl, a town in the northern Puntland region of Somalia.

U.S. navy spokesman Lt. Nathan Christensen said the closest U.S. ship at the time of the hijacking was 555 kilometres away.

The Combined Maritime Forces issued an advisory Wednesday highlighting several recent attacks that occurred hundreds of kilometres off the Somali coast and stating that merchant mariners should be increasingly vigilant when operating in those waters.

Since January, pirates have staged 66 attacks, and they are still holding 14 ships and 260 crew members as hostages, according to the International Maritime Bureau, a watchdog group based in Kuala Lumpur.

There are fewer than 200 U.S.-flagged vessels in international waters, said Larry Howard, chair of the Global Business and Transportation Department at SUNY Maritime College in New York.