When U.S. military airstrikes hit a Doctors Without Borders hospital in the Afghan city of Kunduz on Saturday, uninjured staff scrambled to save everyone they could.But the aftermath was devastating: 12 staff and 10 patients, including three children, were killed in the bombing conducted by U.S. military forces. And 37 more, including 19 staff, were injured."In Kunduz, our patients burned in their beds. Our doctors, nurses, and other staff were killed as they worked," Jason Cone, the group's U.S. executive director, said at a news conference at Doctors Without Borders' New York office on Wednesday. "Our colleagues had to operate on each other. One of our doctors died on an improvised operating table — an office desk — while his colleagues tried to save his life."Now, as they mourn colleagues and patients lost in the strike, the organization is demanding answers — and accountability — from U.S. and Afghan officials.Doctors Without Borders, known internationally as Médecins Sans Frontières, or MSF, called for a first-of-its-kind independent investigation into whether the strike constituted a violation of international humanitarian law.The bombing, Cone said, "was not just an attack on our hospital, it was an attack on the Geneva Conventions.""This cannot be tolerated," he said. "These conventions govern the rules of war and were established to protect civilians in conflict, including patients, medical workers, and facilities. They bring some humanity into what is otherwise an inhumane situation."Sunday's strike came amid renewed conflict and violence in the region. Doctors Without Borders, which reported treating nearly 400 wounded people since the fighting intensified late last month, said it had informed U.S. officials that it was operating a hospital at the site of the bombing as recently as September 29.Staff on the ground reported no fighting at the hospital or advanced warning ahead of the strike, Cone said.