Gunmen in northwestern Pakistan shot and killed a female polio worker as she was returning home on March 2 after taking part in the country's latest anti-polio campaign, police said.
There was no immediate claim of responsibility for the attack.
Militants often target polio teams and police assigned to protect them in Pakistan, falsely claiming the vaccination campaigns are a Western conspiracy to sterilize children.
The March 2 attack happened on the outskirts of the city of Peshawar. Iqra Iqbal was gunned down on her way home, said Iftikhar Khan, a police official.
Pakistan regularly launches anti-polio campaigns in an effort to eradicate the highly infectious disease.
The latest five-day drive against polio started on February 28.
Since January last year, Pakistan has not reported any new cases, raising hopes the Islamic nation is close to becoming a polio-free country.
Pakistan and Afghanistan are the only remaining countries in the world still trying to eradicate polio, which can cause severe paralysis in children.