WARNING - VIDEO CONTAINS GRAPHIC CONTENT<br/> <br />Ambulances take away the bodies of health workers in Karachi, Pakistan, shot by gunmen during an anti-polio drive on Tuesday.<br/> <br />Three women were killed and one man wounded in seperate shootings.<br/> <br />It was not clear who was behind the attack, but Taliban insurgents have repeatedly denounced the anti-polio immunisation campaign as a Western plot to sterilise Muslims.<br/> <br />The team had received telephone calls warning workers they would regret helping the "infidel" campaign against polio.<br/> <br />Another anti-polio worker in Karachi was shot dead on Monday.<br/> <br />And in the northwestern city of Peshawar on Tuesday, gunmen shot a 17-year-old girl supervising an anti-polio campaign there.<br/> <br />She later died in hospital.<br/> <br />Polio attacks the nervous system and can cause permanent paralysis within hours of infection.<br/> <br />At least 35 children in Pakistan have been infected this year.
