U.S. military and administration officials are speaking cautiously as emergency evacuations of U.S. and European nationals, as well as Special Immigration Visa applicants, continue from Hamid Karzai International Airport in Kabul, Afghanistan. The caution is warranted. Officials can’t say how many U.S. citizens are awaiting evacuation, whether they can make it safely to the airport, and most importantly, whether the Taliban will grant them access through checkpoints that surround the secured airport. Doug McKelway has more.