BANGKOK—International aid group Save the Children said two of its staffers were missing in a massacre in eastern Burma that left more than 30 people, including women and children, dead and burned in their vehicles after they were reportedly shot by government troops as they were fleeing combat. Photos of the aftermath of the Christmas Eve killings in Mo So village, just outside Hpruso township in Kayah state, spread on social media in the country, fueling outrage against the military that took power in February after ousting the elected government of Aung San Suu Kyi. The accounts could not be independently verified. The photos showed the charred bodies of over 30 people in three burned-out vehicles. On Sunday, the U.S. Embassy in Burma said it was appalled by the “barbaric attack in Kayah state that killed at least 35 civilians, including women and children.” “We will continue to press for …