investigating the exact cause. the president hamid karzai has confirmed the casualties. this is the highest number of casualties in one incident during the decade-long war. for the first time the u.s. has lost its top credit rating. the u.s. rating has been down graded from triple a to double-a plus by standard and poors. >> the s&p down grade men's for the first time in u.s. history the u.s. has a credit score hats less than perfect. it's a unprecedented black mark on a global scale. >> it's a sad day in the united states to see something like this happen. >> she runs econ no syst...