Gunmen shot dead two women in the Pakistani city of Quetta on Thursday while they were giving polio immunisation drops to children.

No group has claimed responsibility for the attacks yet, but Islamist militants are known to carry out such attacks as they oppose immunisation as un-Islamic. They say immunisation is a foreign ploy to sterilise Muslim children.

The gunmen were riding a motorcycle when they shot Sakina Bibi, 50, and her daughter Alizah, 20, Reuters reported, quoting police official Naseebullah Khan. The women died on their way to a hospital.

The women were participating in an immunisation campaign in five districts of Balochistan province, Khan said.

Prime Minister Shahid Khaqan Abbasi condemned the attack and has ordered an investigation. “Polio teams are rendering a huge national service to save our children from the crippling disease,” his office said. “Attack on these dedicated workers, risking their lives for their nation, is an attack on our future.”