Two female volunteers and a nurse working door to door to vaccinate children against polio were shot dead by gunmen in two separate incidents in the Afghan city of Jalalabad on Tuesday. On the same day, government officials confirmed that an explosion had rocked Jalalabad’s health ministry headquarters but no casualties were reported. In the first incident, the gunmen shot a polio worker at about 11.30am local time as she worked in the Majboor Abad area. The second attack took place less than an hour later when two female polio workers were killed in the city’s Lal Qasim Agha area. No group has claimed responsibility for the attack. A Taliban spokesperson, Zabiullah Mujahid, sent a message to the Guardian stating: “Taliban did not attack the female polio workers.” The murders came a day after the government launched a national vaccination campaign against polio. Hospital officials identified the women by their first names only as Basira, Samina and Negina and said two of them were volunteers, and that the other was a nurse. A health ministry spokesperson in Nangarhar province said the vaccination programme had been temporarily suspended. The latest targeted killings took place as hundreds of polio vaccination teams, many of them made up of volunteers, set out to help in the fight against the virus. “The assassination of three female aid workers is an act and crime against humanity and targeting them is condemnable and needs international-level investigations,” said Orzala Ashraf Nemat, an Afghan women’s rights activist. “The targeting of female workers in the same areas is frequent. It is extremely tragic to see such soft targets are used for political pressure by certain groups on the government,” she said. “Unfortunately, Afghan leaders and international diplomats alike restrict their reactions to condemning it, but what actions can we take to stop this kind of massacre of ordinary Afghans, especially of women?” said Nemat. Teams of polio workers are frequently targeted by militants, including the Taliban, which remain a major hurdle in vaccination efforts. In the past, Mujahid, the Taliban’s spokesman, has maintained that the militants’ leadership were having talks with the World Health Organization to find a way to accommodate polio vaccination drives in areas the group controls. In the past three years polio cases have increased and efforts to eradicate the disabling disease present a tough challenge in the two remaining countries where it is endemic – Afghanistan and Pakistan. Vaccinations in both countries are carried out by female staff and volunteers, as the only ones able to gain access to whole households, including women and children. According to Unicef, 56 new cases of poliovirus were reported in Afghanistan last year, the highest number since 2011.