also developing, in the city of kunduz a humanitarian crisis growing more dire by the hour. it comes after a suspected u.s. air strike blew apart a doctors without border yesterday. the humanitarian group is pulling out. the pentagon acknowledges a strike happened there and is not ruling out the possibility of collateral damage. jon yang is following the latest. conflicting reports about why this happened and who's to blame. what do we know? >> defense secretary ash carter told reporters traveling with him that the situation in his words is complicated and confused. and that's an understatement we know at the same time the united states report that they were