Attack on Polio Workers in Pakistan Kills Two

A Pakistani schoolgirl, who was displaced with her family from Pakistan's tribal areas due to fighting between militants and the army, receives a polio vaccine from a health worker in the outskirts of Islamabad, Pakistan, January 31, 2013.

Pakistani schoolgirls listen to their teacher, not seen, as a health worker visits their school to give them polio vaccines in the outskirts of Islamabad, Pakistan, January 31, 2013.

Pakistani schoolchildren look for their shoes while other enter a classroom as a health worker visits their school to give polio vaccines, in a poor neighborhood on the outskirts of Islamabad, Pakistan, January 31, 2013.

Pakistani relatives and mourners of a polio worker, who was killed in a roadside bomb, pray next to his body, in Parachinar, Pakistan, January 31, 2013.

A policeman stands guard as Neila gives polio vaccine drops to a child at a Christian colony slum in Islamabad, Pakistan, December 20, 2012.

A polio worker gives polio vaccine drops to a child in Lahore, Pakstian, December 20, 2012.

A policeman accompanies polio workers during their anti-polio drive mission in Lahore, Pakistan, December 20, 2012.

A health worker visits Lahore's slums to administer the polio vaccine to infants, Pakistan, December 19, 2012.

Nishat gives polio vaccine drops to a girl in Lahore, Pakistan, December 20, 2012.

A girl shows a finger marked after being immunized in Lahore, Pakistan, December 19, 2012.