Civilians at risk as cease-fire collapses in Aleppo
A new humanitarian crisis is unfolding in the Syrian city of Aleppo, after a day-old cease-fire appeared to fall apart. Rebels and pro-government troops on the verge of retaking the whole city are attacking each other with gunfire and shelling. The United Nations warns of "a complete meltdown of humanity." The rebels are holed up among thousands of civilians in a sliver of territory in the East. Holly Williams reports from Istanbul, Turkey.