This image made from AP video shows the scene moments after a car bomb exploded in front of the Provincial Reconstruction Team in Qalat in Afghanistan's Zabul province on Saturday, April 6, 2013. Six American troops and civilians and an Afghan doctor were killed in attacks on Saturday in southern and eastern Afghanistan as the U.S. military's top officer began a weekend visit to the country, officials said. (AP Photo via AP video)

Photo by: APTN

This image made from AP video shows the scene moments after a car bomb exploded in front of the Provincial Reconstruction Team in Qalat in Afghanistan's Zabul province on Saturday, April 6, 2013. Six American troops and civilians and an Afghan doctor were killed in attacks on Saturday in southern and eastern Afghanistan as the U.S. military's top officer began a weekend visit to the country, officials said. (AP Photo via AP video)