A wounded Afghan police officer is helped from the scene of Friday's explosion and gunfire in Kabul. Omar Sobhani /Reuters /Landov hide caption

itoggle caption Omar Sobhani /Reuters /Landov

The scene Thursday in Kabul, Afghanistan, after a suicide bomber attacked a NATO convoy. Zhao Yishen /Xinhua /Landov hide caption

itoggle caption Zhao Yishen /Xinhua /Landov

A man grieves as others try to help victims and remove bodies from the scene in Kabul earlier today (Dec. 6, 2011) after a suicide bomb exploded in a crowd of Shiite worshipers. Massoud Hossaini /AFP/Getty Images hide caption

itoggle caption Massoud Hossaini /AFP/Getty Images

Afghan Security personnel stand above the body of one attacker, on the 10th floor of the building in Kabul from which RPGs and other weapons were fired. David Gilkey/NPR hide caption

itoggle caption David Gilkey/NPR