NAIROBI, Kenya The American captain held hostage by four Somali pirates made a desperate escape attempt today but was recaptured, and officials said other pirates sought to reinforce their colleagues by sailing hijacked ships with other captives aboard to the scene of the standoff.

The U.S. also was bolstering its force by dispatching other warships to the site off the Horn of Africa, where a U.S. destroyer shadowed the drifting lifeboat carrying the hostage, Capt. Richard Phillips.

The pirates on the lifeboat apparently fear being shot or arrested if they hand over Phillips who was taken hostage in their failed effort to hijack the cargo ship Maersk Alabama on Wednesday and they hope to link up with their colleagues who are using Russian, German, Filipino and other hostages captured in recent days as human shields.

Around midnight local time, Phillips jumped off the lifeboat and began swimming, but was recaptured by the pirates, according to Defense Department officials, speaking on condition of anonymity because they are not authorized to talk about unfolding operations.

Sailors aboard the USS Bainbridge, which is patrolling nearby, were able to see Phillips moving around and talking after his return to the lifeboat, and the Defense Department officials think he is unharmed.

Negotiations are taking place between the pirates and the captain of the Bainbridge, who is getting direction from FBI hostage negotiators, the officials said. The captors are also communicating with other pirate vessels by satellite phone, officials said.

U.S. Central Command chief Gen. David Petraeus said U.S. warships also are headed to the area, more than 300 miles off Somalia's Indian Ocean coast.

"We want to ensure that we have all the capability that might be needed over the course of the coming days," he said.

Mohamed Samaw, a resident of the pirate stronghold in Eyl, Somalia, who claims to have a "share" in a British-owned ship hijacked Monday, said four foreign ships held by pirates are heading toward the lifeboat. A total of 54 hostages are on two of the ships citizens of China, Germany, Russia, Ukraine, the Philippines, Tuvalu, Indonesia and Taiwan.

"The pirates have summoned assistance skiffs and mother ships are heading toward the area from the coast," said a Nairobi-based diplomat, who spoke on condition on anonymity because he is not authorized to talk to the media. "We knew they were gathering yesterday."

Samaw said two ships left Eyl on Wednesday. A third sailed from Haradhere, another pirate base in Somalia, and the fourth one was a Taiwanese fishing vessel seized Monday that was already only 30 miles from the lifeboat.

He said the ships include the German cargo ship Hansa Stavanger, seized earlier this month. The ship's crew of 24 is made up of five Germans, three Russians, two Ukrainians, two Filipinos and 12 from Tuvalu.