QUETTA, Pakistan — Gunmen on motorcycles fatally shot four members of a team dispensing polio vaccines to children, police and hospital officials in Pakistan said on Wednesday. The victims included three women. Three other people were injured in the attack near Quetta in the restive province of Baluchistan on the border with Afghanistan. "Four were killed, including three women," the head of Baluchistan's health service Naseer Baloch told reporters.

Islamist militants have long opposed the vaccination campaign, with some saying it is aimed at sterilizing Muslims. Attacks targeting aid workers intensified when it emerged that Dr. Shakil Afridi, a Pakistani physician, ran a fake vaccination campaign to collect DNA samples from Osama bin Laden and his family to prove his presence there to the CIA. Around 85 percent of all cases worldwide were recorded in Pakistan in 2013. The crippling disease, which affects the nerves in the muscles necessary for breathing, causing respiratory difficulty and paralysis of the arms and legs.

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- Mujeeb Ahmed

The Associated Press contributed to this report