By ROD NORDLAND and SHARIFULLAH SAHAK
It was the worst loss of life among American troops in the capital in several years.
The attack on the bus, known as a Rhino because of its heavy armor, took place in front of the American University on a route often traveled by military trainers from NATO bases in downtown Kabul to the Kabul Military Training Center. At least eight civilians were reported among the dead, including three Afghan police officers and two children.
A military dog was also killed, the military official said.
A Taliban spokesman, Zabiullah Mujahid, claimed responsibility, saying that a suicide bomber named Abdul Rahman Hazarbos drove a truck with 1,500 pounds of explosives into a bus carrying foreign military trainers, killing all aboard. He claimed 25 NATO soldiers were killed in all.
In addition, three Australian NATO soldiers were killed on Saturday by an Afghan soldier who turned his weapon on them, Afghan officials said.
In Kabul, one eyewitness said he saw six dead American soldiers inside the bus, which was completely burned from the explosion, and the Kabul police chief confirmed that some Americans were killed in the attack. Afghan authorities at the scene refused to give details on the incident, cordoning off a site on busy Darulman Road in the capital. At least two NATO medical-evacuation helicopters landed and took off again.
A spokesman for the NATO-led International Security Assistance Force confirmed that the attack had caused casualties, both to NATO forces and to civilians, but would not provide details about the victims or their nationalities.
The attack on the Australians took place in the Nish District of Kandahar Province, at a forward operating base used by Australian troops to train the Afghan National Army. Gen. Abdul Hameed, the commander of the Afghan National Army's 205th Corps, said an Afghan Army trainee opened fire on his Australian trainers, killing three of them as well as an Afghan interpreter. At least nine others were wounded, General Hameed said, seven of them Australians.
"We don't know the cause of this shooting yet, and we are investigating," he said. "The soldier was not new, the first phase of his training was completed and he was in the second phase of his training."
Other Afghan soldiers killed the attacker, he said.
A statement by the NATO-led forces said two International Security Assistance Force service members were killed in the incident, along with the attacker.
In Kabul, a witness at the scene of the bus attack, Ghulam Sakhi, 32, a taxi driver, said he saw the bodies of six badly burned foreign soldiers in the wreckage of the bus. The bus had been blown onto its side and was completely charred. In addition, there were several civilian victims nearby, he said.
The Kabul police chief, Gen. Mohammad Ayoub Salangi, said that American soldiers initially prevented Afghan authorities from going to the scene of the attack, so he did not know how many were killed, although he said he did see both wounded and dead being evacuated by helicopter.
A coalition spokesman, Sgt. First Class Michael Montello, confirmed the Kabul attack but declined to identify the nationalities of the soldiers who died.
There were three other serious violent incidents reported around the country on Saturday. Insurgents attacked a NATO and Afghan military convoy in eastern Nangarhar province on Friday, Sgt. Montello said, and 30 attackers were killed in an ensuing gunfight and airstrikes.
In Khost, unknown gunmen opened fire on a car Friday night, killing four of the occupants, all of them drivers for NATO supply vehicles, said Col. Zeyarat Gul Azans, spokesman for the Khost police chief.
Also on Saturday, a young female suicide bomber on foot attacked government offices in eastern Asadabad city, wounding four, according to the chief of security for Kunar Province, Abdul Sabor Allayar. Guards at the Afghan intelligence service spotted the woman, who was wearing a burqa, and shot her to death before she could get close enough to cause much harm, he said.