Gunmen who attacked a maternity hospital in Kabul came “with the purpose of killing mothers in cold blood”, systematically shooting every woman in labour and new mothers they came across, the charity Médecins Sans Frontières has said. The attack on Tuesday morning, aimed at the youngest of children and most vulnerable of women, shocked even a country that has endured decades of bloodshed and tens of thousands of civilian deaths. On Friday a top US official blamed the local Islamic State affiliate for the killings, and urged the Taliban and Afghan authorities to return to peace talks that have been crumbling since the slaughter. MSF, the NGO that has run the maternity unit for six years, has released more details of an assault it described as “four hours of hell”. Perhaps most chilling, is evidence that pregnant women and babies were targets from the start. The gunmen headed straight to the maternity section when they burst into the hospital, even though other buildings and wards were closer to the entrance. “They came to kill the mothers,” sadi Frederic Bonnot, MSF’s head of programmes in Afghanistan. “They went through the rooms, shooting women in their beds. It was methodical.” Three women were killed in the delivery room, dying shortly before their unborn babies should have drawn their first breaths. Eight were killed in hospital beds, and five others were injured, the charity said in a statement. Ten who found shelter in hospital safe rooms with some staff survived, one giving birth as the attack raged around her. “It’s shocking. We know this area has suffered attacks in the past, but no one could believe they would attack a maternity [ward],” Bonnet said. The total death toll was 24, including a midwife and two young boys. Two of the babies were also wounded, with one needing emergency surgery in another hospital after being shot in the leg. No group has claimed responsibility, with the Taliban condemning the attack and denying any role. But Afghan authorities and analysts say the militants’ campaign of violence created an “enabling environment” for the attack. In its wake, a US-brokered peace process between the Taliban and Afghan authorities is falling apart. Ashraf Ghani, the Afghan president, ordered troops back on the offensive from an “active defence” stance adopted to prepare for talks, and the Taliban has ended a de facto urban ceasefire with a truck bomb in the eastern city of Gardez. Zalmay Khalilzad, an American envoy, said on Friday that Islamic State was behind the hospital attack, although the group’s regional affiliate has not claimed it, and urged the Taliban and Afghan government to put negotiations back on track. “Rather than falling into the Isis trap and delay peace or create obstacles, Afghans must come together to crush this menace and pursue a historic peace opportunity. No more excuses. Afghans, and the world, deserve better,” he said on Twitter. He did not provide any evidence, and the announcement was met with scepticism inside Afghanistan and beyond, where many saw an unseemly rush to get peace talks back on track before the US presidential election. “That is a very quick assessment,” said Saad Mohseni, the director of Moby, Afghanistan’s largest independent media group. “Afghan intelligence sources, who have a better understanding of issues, have indicated to us that they require more time before they can determine who was behind this massacre. Let’s not rush into blaming or exonerating any group just yet.” Ahmad Shuja, director general for international affairs on Afghanistan’s national security council, warned the US risked “normalising murder”. “Sanitising the Taliban’s image and overlooking their bad behaviour when they’ve taken no actual steps for peace is dangerous,” he said on Twitter. “It doesn’t promote peace. Normalising a group involved in the murders of all our citizens normalises murder. There are better ways to support peace efforts.”