Two dozen U.S. special forces killed early Saturday in Afghanistan were on a mission to rescue another team of military personnel pinned down by insurgents, a U.S. military official told CNN.
The helicopter that went down in eastern Afghanistan carried 31 Americans, including 22 Navy SEALs, who were part of a "quick reaction force" sent in to pick up others engaged in a fierce firefight, the official said.
In the single deadliest incident since the start of the decade-long Afghan war, an Army Chinook carrying a team of U.S. special forces and U.S. and Afghan soldiers went down in Wardak province. Insurgents are believed to have shot down the helicopter, a military official said.
The majority of the Navy SEALs who died belonged to the same covert unit that conducted the raid that killed Osama bin Laden in May, though they were not the same men, the official said.
"It's a big loss" for the SEALs, one of the officials said. "The numbers are high."
Afghan President Hamid Karzai issued a statement saying as many as 31 U.S. special forces and seven Afghans were killed.
Special forces have been conducting almost daily night-time raids against insurgent targets in rugged areas like Wardak.
The Chinook went down as an Afghan and coalition force operation targeted a bomb-making cell leader in Wardak, leading to the detention of numerous insurgents Friday, according to NATO's International Security Assistance Force. It is not clear if the helicopter incident and the raid were connected.
The Taliban claimed militants downed the helicopter with a rocket-propelled grenade. Mohammad Hazrat Janan, head of the provincial council, said Tangi village elders reported that insurgents shot at the craft when it was returning from an operation.
Officials are being especially tight-lipped because recovery operations at the site are still underway and body identifications and family notifications are just beginning, a U.S. military official said.
ISAF has not said how the incident occurred. ISAF spokesman Justin Brockhoff confirmed the crash and acknowledged the helicopter had been flying in an area where there was reported insurgent activity, but declined to offer additional details.
The U.S. Embassy in Kabul, which said the helicopter went down Friday evening, said ISAF "is still assessing the circumstances that resulted in these deaths."
Afghan Defense Ministry spokesman Zahir Azimi said it's too early to say if the Taliban caused the crash. He called for an investigation.
Karzai, President Barack Obama and others offered condolences.
"Information is still coming in about this incident. I think it's important that we allow investigators to do their work before jumping to too many conclusions," said Adm. Mike Mullen, chairman of the Joint Chiefs of Staff.
"It's also important that we respect the process of notifying family members, no matter how long that takes. We ought to remember that the troops we lose in this war aren't just statistics or numbers on a wall. They were parents and siblings, and someone's child. We need to make sure we do all we can to comfort and support the families whose lives are now forever changed."
Obama was first notified of the incident at 8 p.m. Friday, a White House official told CNN. He led a telephone briefing midmorning Saturday.
The CH-47 Chinook is the workhorse helicopter of the Army, used for decades to haul large numbers of troops and quantities of equipment.
The military is looking into whether the helicopter was vulnerable to being shot down.
Depending on the configuration, the tandem-rotor Chinook can carry 33 to 55 troops, plus two pilots on the flight deck, according to Jane's Defence Equipment and Technology. It is capable of speeds up to 159 mph. The front rotor turns counter-clockwise while the rear rotor turns clockwise.
The SEALs, described as the "best of the best," have been lauded for killing al Qaeda terror leader Osama bin Laden in May, one of the most celebrated military acts in recent history.
SEALs, short for Sea, Air and Land teams, originated in World War II when the United States realized that to invade Japan, it needed savvy, quick-thinking fighters who could perform reconnaissance at sea. They became known as highly trained jack-of-all-trade commandos.
The SEALs, and other special forces, are given dangerous missions and go after insurgents in remote areas. A huge amount of money, training and expertise is poured into their careers. Along with carrying out counter-terrorism assaults on the Afghan-Pakistani border, they conduct training and military missions around the world.
The U.S. deaths come just as NATO is drawing down and handing over security control to national forces. Ten thousand U.S. troops are scheduled to depart by year's end, with all U.S. military personnel out of Afghanistan by the end of 2014. However, no one is talking about withdrawing special forces and they are expected to stay on the job.
"We are determined to stay the course, especially in this crucial period when Afghan and international security forces are working closer than ever to make transition a success," NATO Secretary-General Anders Fogh Rasmussen said.
The Afghan street is buzzing with reflection about the significance of the incident.
"It shows that the Taliban are very strong and have not been defeated by the U.S.," said Kabul resident Saifurahman Ahmezai.
But others said the incident is not emblematic of a new-found insurgent strength.
"The Taliban are not that powerful," said Hezat, a police officer in Kabul who goes only by one name. "But if the international forces leave Afghanistan, the situation will get even worse."
Last month, a NATO helicopter was brought down by insurgent fire in the country's eastern province of Kunar. The Taliban also claimed responsibility for that attack, though no injuries were reported.
In a separate incident, a NATO service member died Saturday after an improvised explosive device detonated in southern Afghanistan.
Elsewhere Saturday, a joint Afghan and coalition force conducted raids in the eastern province of Nangarhar, killing "several insurgents," NATO reported.
The operation also targeted a "Taliban facilitator," who NATO said was responsible for supplying ammunition and bomb-making materials to the Taliban.
In July, a series of gun battles in Nangarhar between insurgents and NATO forces left at least 10 militants dead.
There are 150,000 ISAF forces in Afghanistan, including nearly 100,000 from the United States -- the largest NATO presence in the region since the U.S.-led war began in 2001.
Source: CNN