KABUL, Afghanistan - Insurgents shot down a US military helicopter during fighting in eastern Afghanistan, killing 30 Americans, most of them belonging to the same elite Navy SEALs unit that killed Osama bin Laden, as well as seven Afghan commandos, US officials said Saturday. It was the deadliest single loss for American forces in the decade-old war.

The downing was a stinging blow to the lauded, tight-knit SEAL Team 6, months after its crowning achievement. It was also a heavy setback for the US-led coalition as it begins to draw down thousands of combat troops fighting what has become an increasingly costly and unpopular war.

US President Barack Obama holds a conference call from Camp David, Maryland, in this August 6, 2011 photo release. A NATO helicopter crashed during a battle with the Taliban in Afghanistan, killing 30 Americans and seven Afghans, the Afghan president said on Saturday, the deadliest single incident for foreign troops in 10 years of war. [Photo/Agencies]

None of the 22 SEAL personnel killed in the crash were part of the team that killed bin Laden in a May raid in Pakistan, but they belonged to the same unit. Their deployment in the raid in which the helicopter crashed would suggest that the target was a high-ranking insurgent figure.

Special operations forces, including the SEALs and others, have been at the forefront in the stepped up strategy of taking out key insurgent leaders in targeted raids, and they will be relied on even more as regular troops pull out.

The strike is also likely to boost the morale of the Taliban in a key province that controls a strategic approach to the capital Kabul. The Taliban claimed they downed the helicopter with a rocket while it was taking part in a raid on a house where insurgents were gathered in the province of Wardak overnight. Wreckage of the craft was strewn across the crash site, a Taliban spokesman said.

A senior US administration official in Washington said it appeared the craft had been shot down. The official spoke on condition of anonymity because the crash is still being investigated.

"Their deaths are a reminder of the extraordinary sacrifices made by the men and women of our military and their families, including all who have served in Afghanistan," US President Barack Obama said in a statement, adding that his thoughts and prayers go out to the families of those who perished.

The US-led coalition said in a statement that 30 American service members, a civilian interpreter and seven Afghan commandos were killed when their CH-47 Chinook crashed in the early hours Saturday. A current US official and a former US official said the Americans included 22 SEALs, three Air Force air controllers and a dog handler and his dog. The two spoke on condition of anonymity because military officials were still notifying the families of the dead.

Afghan President Hamid Karzai announced the number of people killed in the crash and the presence of special operations troops before any other public figure. He also offered his condolences to the American and Afghan troops killed in the crash.

The deaths bring to 365 the number of coalition troops killed this year in Afghanistan and 42 this month.

The overnight raid took place in the Tangi Joy Zarin area of Wardak's Sayd Abad district, about 60 miles (97 kilometers) southwest of Kabul. Forested peaks in the region give the insurgency good cover and the Taliban have continued to use it as a base despite repeated NATO assaults.

Taliban spokesman Zabiullah Mujahid said in a statement that the helicopter was involved in an assault on a house where insurgent fighters were gathering. During the battle, the fighters shot down the helicopter with a rocket, he said.

An American official in Brussels said the helicopter was a twin-rotor Chinook, a large troop and cargo transporter.

The casualties are believed to be largest loss of life in the history of SEAL Team Six, officially called the Navy Special Warfare Development Group, or DEVGRU. The team is considered the best of the best among the already elite SEALs, which numbers 3,000 personnel.