At least 12 Americans were among the 17 people killed when a suicide bomber drove a car into a NATO vehicle in Kabul, U.S. officials say. It was the single deadliest attack for Americans in Kabul since the war began. Killed were five U.S. soldiers, eight American contract workers, and four Afghans. The Taliban has claimed responsibility for the attack, the deadliest in the country for U.S. forces since the helicopter crash in August that killed 38 people. Saturday's attack was one of four in the past two days, including a shooting that killed three Australians, and an incident in which a woman in northeastern Afghanistan blew herself up near the Afghan intelligence agency, wounding four people.