Updated

The CIA said Thursday that seven of its employees were killed and six others wounded in a homicide bombing at a base in Afghanistan. The Associated Press has learned that one of them was the chief of the CIA's post in Afghanistan's southeastern Khost Province.

CIA Director Leon Panetta said in a message to agency staff that the casualties sustained in Wednesday's strike at Forward Operating Base Chapman were the result of a terrorist attack.

Initial reports indicated that eight American civilians had been killed. There was no explanation for the discrepancy in Panetta's message, which was released by the CIA in an unusual step a day after one of the deadliest attacks on the agency in its history.

"Those who fell yesterday were far from home and close to the enemy, doing the hard work that must be done to protect our country from terrorism," Panetta said. "We owe them our deepest gratitude, and we pledge to them and their families that we will never cease fighting for the cause to which they dedicated their lives — a safer America."

"Yesterday's tragedy reminds us that the men and women of the CIA put their lives at risk every day to protect this nation," he said. "Throughout our history, the reality is that those who make a real difference often face real danger."

No further information about the victims would be released," the CIA director said, "due to the sensitivity of their mission and other ongoing operations."

Separately, former CIA officials said an agent who ran the agency's base in Khost was among those killed by the attacker, who detonated a bomb-laden vest inside the compound.

Former CIA officials say the Khost chief was the mother of three. As base chief she would have directed and coordinated CIA operations and intelligence gathering in the province, a hotbed of Taliban and insurgent activity because of its proximity to Pakistan's lawless tribal region.

The former officials spoke on condition of anonymity because they were not authorized to speak publicly.

The Taliban claimed responsibility Thursday for the bombings that killed 14 people, including eight Americans and an Afghan in a homicide attack in the volatile east, and five Canadians in the south.

It was unclear how the bomber at U.S. Forward Operating Base Chapman at the edge of Khost city was able to circumvent security. Khost is the capital of Khost province, which borders Pakistan and is a Taliban stronghold.

Taliban spokesman Zabiullah Mujahid said in a statement that an Afghan National Army officer wearing a homicide vest entered the base and blew himself up inside the gym. A U.S. official who was briefed on Wednesday's blast also said it took place in the gym.

Harold E. Brown Jr., a State Department employee of Fairfax, Va., died in the attack, his father, Harold E. Brown Sr., told The Associated Press on Thursday. The younger Brown, 37, who grew up in Bolton, Mass., served in the Army and remained a major in the reserves. He is survived by a wife and three children ages 12, 10 and 2.

Separately, four Canadian soldiers and a journalist embedded in their unit were killed the same day by a roadside bomb in the southern Kandahar province, the bloodiest single incident suffered by the Canadian military in 2009.

Michelle Lang, a 34-year-old health reporter with the Calgary Herald, was the first Canadian journalist to die in Afghanistan. She arrived in the country just two weeks ago.

There was no independent confirmation that the bomber in the attack on the U.S. base was a member of the Afghan military. Gen. Mohammad Zahir Azimi, spokesman for the Afghan Ministry of Defense, said no Afghan National Army soldiers are at the base.

But an Afghan official in Khost said the U.S. has hired about 200 Afghans to help with security at the base. They are usually deployed on the outer ring of its walls, although some work inside, the official said on condition of anonymity because of the sensitivity of the issue.

"It's not the first time that Afghan forces have conducted such an attack to kill Americans or foreigners," the Taliban statement said, citing the alleged killing of an American soldier and the wounding of two Italians this week in Badghis province. NATO has provided no details of that incident, but Afghan Gen. Jalander Shah Bahnam said an Afghan soldier opened fire on a base in the province's Bala Murghab district.

A former senior CIA officer who was stationed at the base said a combination of agency officers and contractors operated out of the remote outpost with the military and other agencies.

NATO said only that the base is used by provincial reconstruction teams, which consist of both soldiers and civilians, and other personnel.

A spokesman in Kabul for the international coalition force said no U.S. or NATO troops were killed in the explosion. The attack was the deadliest for Americans since eight soldiers were killed in an insurgent attack on a base in eastern Afghanistan on Oct. 3.

Only four known CIA operatives have been killed in Afghanistan since the Sept. 11, 2001 terrorist attacks. CIA officer Micheal "Mike" Spann was killed in a prison uprising in November 2001. An agency officer died in a training exercise in 2003, and two contractors operating out of a CIA base in Shkin district of Paktika province were killed the same year.

In Wednesday's other attack on Westerners, NATO said the four Canadian troops and the reporter died when their armored vehicle hit a bomb while on an afternoon patrol south of Kandahar city. It was the third-deadliest day for Canadians in Afghanistan since the war began.

Lang "was one of those journalists who always wanted to get to the bottom of every story so this was an important trip for her," said a Calgary Herald colleague, Colette Derworiz.

The military has not disclosed the names of the Canadian troops because relatives have not all been notified.

Brig. Gen. Daniel Menard, commander of coalition forces in Kandahar, said the soldiers were conducting a community security patrol.

According to figures compiled by The Associated Press, 32 Canadian troops have been killed in Afghanistan this year; in all, 138 have died in the war.

Afghan President Hamid Karzai issued a statement of condolence to Americans and Canadians, saying "your children sacrificed their lives for the people of Afghanistan and the threat of terrorism. The Afghans will not forget your sacrifice."

Also Thursday, a spokesman for the governor of Helmand province in the south said an airstrike by international forces killed and wounded civilians. Dawud Ahmadi said he did not know how many were killed Wednesday in Babajid district. He said the attack took place after an international forces patrol came under fire.

NATO said it was aware of the reports and was investigating. Claims of civilians killed by foreign forces are a highly emotional issue among Afghans and feed strong resentment of international soldiers.

Separately, police said militants beheaded six Afghans for cooperating with government authorities. Juma Gul Hamit, police chief of Uruzgan province in south-central Afghanistan, said the men were killed near the provincial capital of Tarin Kot. He said a seventh victim was being treated for serious neck wounds.