Last updated at 12:44 a.m. EST
Separate bomb explosions Wednesday in Afghanistan's volatile east and south killed eight Americans and four troops and a journalist from Canada, U.S. and NATO officials said.
A suicide attacker detonated explosives at Forward Operating Base Chapman in Khost province near the Afghan border with Pakistan, killing eight American civilians and wounding others, U.S. officials in Washington said. CBS News correspondent David Martin reports that all eight civilians were affiliated with the CIA.
"We mourn the loss of life in this attack, and are withholding further details pending notification of next of kin," U.S. State Department spokesman Ian Kelly said.
Early Thursday morning the Taliban took responsibility for the attack. Taliban spokesman Zabiullah Mujahid told The Associated Press that a Taliban bomber wearing a military uniform and a suicide vest entered the base in Khost and blew himself inside the gym.
A senior U.S. official in Washington said there were conflicting reports on the number of casualties, but that others were injured in the attack. The officials spoke on condition of anonymity because not all details about the incident had been confirmed.
A senior State Department official told The Associated Press on condition of anonymity that all of the victims were civilians. However, that could include military contractors and U.S. intelligence officials.
In Kabul, a spokesman for the international coalition force in Kabul said no U.S. or NATO troops were killed in the afternoon explosion.
The outpost is located in the middle of a notorious stronghold for Afghan insurgents near the border with Pakistan, reports Martin.
Afghan soldiers and civilians are present at almost every American outpost since one of the chief principals of the U.S. strategy is to partner with the Afghans. According to Christine Fair of Georgetown University, some of them.
"They have really become a vehicle of infiltration for the Taliban," Fair told Martin. "This is most certainly a vulnerability in our strategy going forward in trying to hand over security to the Afghans if we don't really have a way of figuring out who we can trust."
In the south, NATO said that the four Canadian troops and a reporter embedded with their unit died when their armored vehicle hit the bomb while on an afternoon patrol south of Kandahar city.
The Canadian Press identified the journalist as Michelle Lang, a 34-year-old health reporter with the Calgary Herald, who was on her first assignment to Afghanistan.
The military has not disclosed the names of the troops because relatives had not all been notified.
"We are all very saddened to hear this tragic news," Alberta Health and Wellness Minister Ron Liepert said in a statement. "Michelle covered health issues with professionalism, accuracy and thoroughness. She was tenacious in her quest to inform Albertans, and for her diligence she was very well respected."
Brig. Gen. Daniel Menard, commander of coalition forces in Kandahar, told Canadian Press early Thursday that the soldiers were conducting a community security patrol in order to gather information about daily life in the area and how to maintain security.
Wednesday was the second lethal strike against the Canadian force in a week. Another Canadian troop and an Afghan soldier were killed Dec. 23 during a foot patrol in Panjwayi district of Kandahar province. According to figures compiled by The Associated Press, the latest casualties bring to 32 the number of Canadian forces killed in Afghanistan this year; in all, 138 have died in the war.
Separately on Wednesday, NATO questioned Afghan reports that international troops killed 10 civilians, including schoolchildren, in a weekend attack that prompted hundreds of angry Afghan protesters to burn an effigy of U.S. President Barack Obama and chant "death" to America.
The head of an investigative team appointed by Afghan President Hamid Karzai told The Associated Press by telephone that eight students between the ages of 12 and 14 were among the dead discovered in a village house in a remote section of Kunar province in eastern Afghanistan. NATO said in a statement released late Wednesday night that while there was no direct evidence to substantiate the claims, the international force had requested and welcomed a joint investigation to reach an "impartial and accurate determination" of what happened in the attack.
Conflicting accounts of what occurred during fighting in Kunar's Narang district prompted an emotional outcry over civilian deaths, one of the most sensitive issues for international troops fighting the more than eight-year-old war. Although insurgents are responsible for the deaths of far more civilians, those blamed on coalition forces spark the most resentment and undermine the fight against militants. With 37,000 more U.S. and NATO troops being deployed to the battle zone, concern over civilian casualties is unlikely to ease anytime soon.
Several hundred Afghans demonstrated in the capital of Kabul and in the eastern city of Jalalabad where the likeness of Obama, adorned with a small American flag, burned on a pole held above demonstrators.
Several hundred Afghans demonstrated in the capital and in the eastern city of Jalalabad where the likeness of Obama, adorned with a small American flag, burned on a pole held above demonstrators. In Kabul, protesters carried signs that read: "Does peacekeeping mean killing children?" and "Stop killing us."
Karzai said in a statement that he talked to the relatives of the Kunar victims to express his condolences and pledge to bring to justice those responsible for the attack.
Asadullah Wafa, a senior adviser to Karzai who led a 10-member investigative team to Kunar province, said he was convinced that all those killed were innocent civilians.
"I have talked to the principal of the school in the village and he gave us details about the killed children," Wafa said. "The schoolchildren cannot be al Qaeda."
The bodies had already been buried by the time Wafa's team arrived on Tuesday.
According to the NATO statement, the initial review by Wafa's delegation "asserted that the dead were unarmed civilians removed by international forces from their homes and shot."
The international force's account of what occurred was much different.
NATO said that on Saturday, a joint coalition and Afghan security force entered the village of Ghazi Khan looking for an insurgent group responsible for a series of violent attacks in the area.
"As the joint assault force entered the village, they came under fire from several buildings and in returning fire killed nine individuals," the NATO statement said. "Several assault rifles, ammunition, and ammonium nitrate used in bomb-making were discovered."
Col. Wayne Shanks, spokesman for NATO's International Security Assistance Force in Afghanistan, said at a news conference Wednesday that the coalition force goes to great lengths to avoid civilian casualties.
The latest figures released by the United Nations show that 2,021 civilians died during clashes in the first 10 months of this year, up from 1,838 for the same period last year. International forces' stepped up efforts to protect the population has reduced civilian casualties. Taliban insurgents were blamed for 68 percent of the deaths this year - three times more than NATO forces, according to the U.N.