ISLAMABAD, Pakistan — A World Health Organization consultant who was conducting a polio vaccination campaign was attacked by unknown assailants in Karachi, Pakistan, on Tuesday, the group said.

Dr. Constant Dedo, who was hired by the WHO’s polio drive, was returning from a routine visit to Gadap, a town in northwestern Karachi, WHO spokeswoman Maryam Yunus said. His vehicle was intercepted by gunmen on a motorbike and shot at; the first bullets struck the tires, rendering the vehicle immobile, Yunus said.

The assailants then fired at the driver, who was struck in the neck and shoulders, and Dedo, who was shot in the abdomen, Yunus said.

“Both were given first aid and shifted to Agha Khan Hospital,” Yunus said. “Their condition is stable, and they are out of danger.”

The motive for the attack was unclear. However, Pakistanis have viewed polio vaccination campaigns with suspicion after the CIA’s use of a fake vaccination program last year to collect DNA samples from residents of Osama bin Laden’s compound to verify the al Qaeda leader’s presence there. Bin Laden was killed by U.S. forces in May 2011.

Dedo, who is from Ghana, has been living in Karachi for some time while working on the anti-polio campaign. The driver was a WHO staffer, Yunus said.

Police were investigating and would interview the driver, she said. It was unclear whether Dedo’s vehicle had a security convoy with it, a routine practice, she said.

WHO officials had informed leaders in Gadap of Dedo’s visit before his arrival, Yunus said.

It was the first time WHO staff has been attacked in Pakistan, she said, but the organization will not suspend operations.