First they took out Osama bin Laden. Now the US Navy SEALs have earned their "special forces" designation once again by conducting a daring, pinpoint rescue of two aid workers held hostage for three months in Somalia.

US officials confirmed it was a Navy SEAL team that carried out the pre-dawn raid, but the Pentagon, citing "operation security reasons," would not confirm US media reports that it was SEAL Team 6, the same unit which got Al-Qaeda leader bin Laden deep inside Pakistan last May.

American Jessica Buchanan and Dane Poul Thisted, who both worked for the Danish Refugee Council Demining Group, were rescued unharmed after helicopter-borne US commandos swooped in on scrubland in central Somalia early Wednesday local time, according to a local Somali official.

They killed all nine of them, the US military said. US Defense Secretary Leon Panetta said no US troops had been wounded or killed in the operation, which was personally authorized by President Barack Obama.

The SEALs -- an acronym of "Sea, Air, Land" -- specialize in reconnaissance and sea-borne assaults, often on vessels. They count some 2,300 highly specialized operatives among their ranks, and their raids mostly involve participation of two teams totaling nearly 30 commandos.

For a decade, they have been putting their elite training to use on the battlefields of Iraq and Afghanistan, as have their US Army counterparts in Delta Force and the Green Berets.

Team 6 is the elite of the elite, and their missions are classified. While its shining moment was the spectacular bin Laden triumph, Team 6 is cloaked in secrecy, and its activities are almost never officially acknowledged.

According to the GlobalSecurity website, SEAL Team 6 is said to have been deployed for a possible -- but never attempted -- rescue of the Achille Lauro cruise ship from hijackers in 1985, and helped free the American captain of the container ship Maersk Alabama amid a 2009 standoff with pirates off Somalia.

According to US media, the elite fighters are also believed to have been involved in the mission to rescue Scottish aid worker Linda Norgrove in Afghanistan after she was kidnapped by members of the Taliban in 2010. Norgrove died in the operation.

Despite the stellar successes of the past year, the SEALs have also known tragedy during the same period.

Seventeen US Navy SEALs, mostly from Team 6, were among 38 people killed last August when the Taliban shot down the Chinook helicopter that was transporting the US personnel, in the deadliest incident for US and NATO forces since the war in Afghanistan began in 2001.

The Team 6 moniker had been chosen by the unit's founder, Richard Marcinko, who wrote in his book "Rogue Warrior" that he wanted to trick other nations, notably the Soviet Union, into believing that the United States had more special operations teams than it actually had.

In the 1980s it had some 90 members, but its size swelled to nearly 300 after the 9/11 attacks of 2001.

While the name Team 6 continues to be used, it has not been the official designation since 1987. The unit was subsequently renamed DEVGRU, the United States Naval Special Warfare Development Group.