Peshawar, Pakistan (CNN) -- Two people were killed and 13 wounded Monday in a bombing that targeted polio workers in northwest Pakistan, police said.
The blast took place on the outskirts of the violence-plagued city of Peshawar.
Najeeb-Ur-Rehman, the senior superintendent of police, said the bomb was remotely detonated as polio vaccines and accompanying materials were being handed out to health workers.
Police had earlier said that six people were killed in the attack.
Pakistan is one of three countries in the world where polio has yet to be eradicated.
Many Pakistanis have viewed polio vaccination campaigns with suspicion after the CIA's use of a fake vaccination program in 2011 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.
Last year, a Taliban commander in northwest Pakistan announced a ban on polio vaccines for children in the region as long as the United States continues its campaign of drone strikes in the region, the Taliban said.
It wasn't immediately clear if the Taliban played a role in Sunday's attacks.
Polio, a highly infectious viral disease that can cause permanent paralysis in a matter of hours, has been eradicated around the world except for three countries where it is endemic: Pakistan, Nigeria and Afghanistan.
After the number of cases spiked sharply last year, Pakistan stepped up its eradication efforts. The numbers fell from 173 in 2011 to 58 in 2012, according to the Global Polio Eradication Initiative.