Reporting from Kabul, Afghanistan, and Rochester, N.Y. -- A bomber slipped into a U.S. base in eastern Afghanistan on Wednesday and detonated a suicide vest, killing eight CIA officers in one of the deadliest days in the agency's history, current and former U.S. officials said.
The attack took place at Forward Operating Base Chapman in Khowst province, an area near the border with Pakistan that is a hotbed of insurgent activity. An undisclosed number of civilians were wounded, the officials said. No military personnel with the U.S. or North Atlantic Treaty Organization forces were killed or injured, they said.
A U.S. official who spoke on condition of anonymity said the CIA had a major presence at the base, in part because of its strategic location.
The Taliban claimed responsibility for the attack in a message posted early today on its Pashto-language website. The statement, attributed to spokesman Zabiullah Mujahid, said the attacker was a member of the Afghan army who entered the base clad in his military uniform. It identified him only as Samiullah.
The casualties highlight the CIA's increasingly important role in Afghanistan, and come as the United States is embarking on a major buildup of its civilian workforce that parallels an increase in troop strength.
President Obama announced early this month that he planned to send 30,000 more troops in an effort to break the momentum Taliban fighters have gained in many parts of the country. The deployment will bring the total U.S. military force there to nearly 100,000.
A former U.S. intelligence official knowledgeable about the bombing said it killed more CIA personnel than any attack since the bombing of the U.S. Embassy in Beirut in 1983. Before Wednesday's attack, four CIA operatives had been killed in Afghanistan, the former official said.
The eight dead were CIA officers, the former official said. "They were all career CIA officials."
The U.S. official said the bomber detonated his explosives vest in an area that was used as a fitness center.
CIA veterans were stunned by the news and at a loss to explain how a bomber was able to penetrate the security.
"It's a forward operating base in a dicey area, but to get a suicide bomber inside the wires -- it's hard to understand how that could happen," the former official said.
Officials said this fall that the agency was deploying spies, analysts and paramilitary operatives in a buildup that would make its station there among the largest in CIA history.
Though the CIA station is based at the U.S. Embassy in Kabul, the bulk of its workforce is scattered among secret bases and military outposts dotting the country. Most CIA personnel in Afghanistan are involved in support functions such as providing security or managing computer systems, rather than in gathering and analyzing intelligence.
But some of the work civilians perform, particularly that involving law enforcement and intelligence gathering, is considered as dangerous as military duty. Three civilian Drug Enforcement Administration agents were killed in a helicopter crash in October in western Afghanistan. They were accompanying troops on a counternarcotics mission.
Khowst province has been a prime target of militants operating in eastern Afghanistan and just across the border in the tribal areas of Pakistan.
The Chapman base is part of NATO's Regional Command East, which is supervised by the U.S. military. It also houses Western civilians working on reconstruction projects.
The main U.S. base in the province, known as Camp Salerno, has been the target of numerous attacks. Bombers have blown themselves up just outside its gates while trying to penetrate the fortified installation. Afghan civilians usually bear the brunt of such attacks.
Last week, Taliban militants with rocket-propelled grenades and suicide vests entered a building near a police station in the nearby city of Gardez, setting off a battle with U.S. and Afghan security forces that lasted through the morning.
Meanwhile Wednesday, military officials said four Canadian soldiers and a Canadian journalist were killed in an explosion in Kandahar province in Afghanistan's south.
The Canadian Press quoted journalists in Afghanistan as saying the journalist was reporter Michelle Lang, 34, of the Calgary Herald.
The death toll among U.S. military forces this year has been the highest since the war in Afghanistan began in October 2001. This year, 311 American troops have been killed, according to the independent website icasualties.org, bringing the death toll for U.S. forces during the war to 941.
A total of 138 Canadian troops have been killed, 32 of them this year, Canadian Press said.