Three US troops, at least 18 Afghans, killed in suicide blast By Cheryll Simpson, NBC News in Kabul KHOST, Afghanistan -- Three U.S. service members, their Afghan interpreter and 17 Afghan civilians were killed by an apparent suicide bomber on a motorbike in the eastern Afghan city of Khost Wednesday, officials said. The United States Embassy in Afghanistan issued a statement saying it "strongly condemns this cowardly attack," which is the second on foreign forces in the troubled province this month. A U.S. official, speaking anonymously to The Associated Press, said the foreign troops killed were Americans. However, a spokesman for the NATO-led International Security Assistance Force (ISAF), said the nationality of the troops would not immediately be confirmed. A local official told NBC News that women and children were among the civilian casualties in the attack, aimed at an American-Afghan military convoy passing through the town. The official said the death toll was likely to rise, and that 32 Afghans suffered injuries. Msnbc.com staff contributed to this report.