Officials in Pakistan say gunmen have killed the driver of a van carrying two polio workers in the country's northwest.
The shooting took place in the restive Khyber tribal region, where the military is battling Taliban and Al-Qaeda linked militants.
Local officials say the polio workers were making preparations ahead of a nationwide antipolio vaccination drive, starting on February 16, when they were attacked.
They escaped unhurt.
No one has yet claimed responsibility, although Islamic extremists have carried out numerous attacks on polio workers in the past.
Militants claim the vaccination campaign is a cover for espionage and a conspiracy to sterilize Muslims.
Pakistan, Afghanistan, and Nigeria are the only three countries in the world where polio remains endemic.