Thirty-three people are still missing five days after a catastrophic U.S. airstrike on a hospital in the Afghan city of Kunduz that has prompted international outrage, medical charity Doctors Without Borders (MSF) said Thursday. Of the missing, nine are patients and 24 are staff, according to Guilhem Molinie, country representative for MSF in Afghanistan. "We are still in shock," Molinie told a news conference in Kabul. "We lost many colleagues and at the moment it's clear that we don't want to take the risk for any of our staff. We don't control the hospital." The strike in the early hours of Oct. 3 killed 12 MSF staff and 10 patients, prompting the charity to close the trauma center, seen as a lifeline in a war-battered region with scant medical care. A New York Times report this week said the top U.S. and NATO commander in Afghanistan thought American forces had broken their own rules of engagement in carrying out the strike. U.S. President Barack Obama Wednesday apologized to MSF head Joanne Liu, admitting the strike was a mistake. Three separate probes – by the U.S. military, NATO and Afghan officials – are under way. But the charity, which has condemned the attack as a war crime, is stressing the need for an international investigation, saying the bombing raid was in contravention of the Geneva Conventions. "We cannot rely on an internal military investigation," Liu said, insisting that the International Humanitarian Fact-Finding Commission should probe the bombing. International aid groups, the U.N. and a growing tide of global revulsion have added to the pressure on Washington to come clean over the strike, which came days after the Taliban overran Kunduz. Hungry, thirsty and war-wounded residents, slowly emerging from their houses Wednesday after days of pitched street battles in the northern city, complained that Kunduz lacked essential medical support. Molinie said Thursday MSF has not received any assurances that would give them the "confidence" to return to Kunduz. "MSF will be reviewing the security conditions of all its operations in Afghanistan," general director Christopher Stokes said. The U.S. asked NATO allies Thursday for flexibility as the alliance reviews its plans to rapidly withdraw troops from Afghanistan, U.S. Defense Secretary Ash Carter said Thursday after talks in Brussels.