At least four people were killed in two separate attacks on polio vaccination teams by unidentified men in Pakistan Tuesday local media reported. Three anti-polio vaccination workers including two women were killed while two injured when some some unidentified people riding motorbikes opened fire at a polio team in the port city of Karachi's Qayummabad area Xinhua reported. No group immediately claimed responsibility for the attack. The latest attack took place a day after Sindh provincial health authorities kicked off a four-day anti-polio drive to vaccinate some 7.6 million children as part of a nationwide campaign against the disease. In another