Kabul, Afghanistan (CNN) -- At least 17 people were killed in central Kabul on Saturday when a suicide bomber struck a vehicle in a military convoy, according to officials.
Five troops and eight civilians were killed in the attack, NATO's International Security Assistance Force said. Afghan officials said four Afghans, including two students, were also killed.
Among the dead was Master Corporal Byron Greff, a Canadian, according to the Canadian Expeditionary Force Command. It was not immediately clear whether he was included in the ISAF-provided figure.
A U.S. military official said earlier that 13 Americans had died, but an ISAF spokesman could not confirm that number.
The U.S. official emphasized details are continuing to unfold. A heavily damaged vehicle was believed to be an armored bus that was carrying U.S. troops from one base to another. A senior NATO official identified it as a custom-built, heavily armored Rhino.
The attack caused a "number" of NATO and local Afghan casualties, ISAF said in a statement. Four Afghans, including two students, were also killed, said Hashmat Stanikzai, spokesman for Kabul's police chief.
Afghan President Hamid Karzai offered his sympathies to the families of the victims in a statement and said the cowardly character of the attack demonstrates "the very evil and heinous nature of the enemy."
A Taliban spokesman confirmed Saturday's attack in a text message, saying it killed "16 foreign soldiers, one civilian" and injured many others.
Taliban casualty counts are often inflated; there was no other reliable indication 16 foreigners were killed.
Stanikzai said the vehicle used in the attack appeared to be a red Toyota Corolla packed with a significant amount of explosives.
It was unclear how many people were wounded, said Sediq Sediqqi, a spokesman for the Interior Ministry.
The U.S. Embassy in Kabul expressed condolences to families and said it will continue the victims' "dedicated work on behalf of peace in this country and region."
"It's a shock. It makes you mad. It makes me angry," said U.S. Ambassador Ryan Crocker. "We are not going to let these guys win."
The attack was one of two targeting NATO-led forces on Saturday.
A gunman wearing an Afghan army uniform turned his weapon on coalition forces during training, killing three and wounding several others, ISAF said. The shooter was killed in the incident in southern Afghanistan.
The coalition did not provide any other details about the shooting, and did not disclose the nationalities of those killed.
In another suicide attack in northeastern Afghanistan, a woman in a burqa detonated herself near the nation's intelligence agency.
She tried to enter the National Directorate of Security and was shot at, but she still managed to detonate herself, said Sabour Alayar, deputy police chief of Kunar province.
Two officers and two civilians were wounded, he said, adding that the female suicide bomber was about 25 years old.
Alayar said they had intelligence of a suicide bomber looking for a target, and their security forces were on alert.
Gen. John R. Allen, commander of ISAF, condemned Saturday's attacks across the country.
"I am both saddened and outraged by the attacks that took place today against Coalition forces and the people of Afghanistan," Allen said in a statement. "The enemies of peace are not martyrs, but murderers. To hide the fact that they are losing territory, support, and the will to fight, our common enemy continues to employ suicide attackers to kill innocent Afghan fathers, mothers, sons and daughters, as well as the Coalition forces who have volunteered to protect them."
The U.S.-led war in Afghanistan marked its 10th year earlier this month having passed two major milestones: The Taliban has been forced out of power and Osama bin Laden is dead.
But Afghanistan has been hit by a wave of high-profile attacks in recent months that have jeopardized the peace negotiations.
September's turban bomb assassination of former Afghan President Burhanuddin Rabbani, revered by many as a father of the Mujahedeen movement that ousted the Soviets in the 1980s, appears to have dealt the biggest blow to the peace process.
Rabbani was the chairman of President Karzai's High Council for Peace, which has been trying for a year to foster dialogue with the Taliban -- a strategy that Karzai publicly abandoned following Rabbani's killing.
Nearly 2,800 troops from the United States and its partners have died during the 10 years of war, according to a CNN count.
CNN Pentagon correspondent Barbara Starr and journalist Ruhullah Khapalwak contributed to this report.