Two policemen protecting the vaccinators were injured in the shooting in Mardan town of Khyber-Pakhtunkhwa province.
One of the policemen died while being taken to hospital, Deputy Inspector General of Police Zafar Khan told reporters.
The other policeman, who sustained serious injuries, was rushed to a hospital in Peshawar, the capital of Khyber-Pakhtunkhwa.
The members of the polio vaccination team were safe, Khan said.
No group claimed responsibility for the attack.
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The banned Tehrik-e-Taliban Pakistan has for long opposed the polio vaccination campaign.
In December, eight volunteers involved in a polio vaccination campaign were gunned down in a string of attacks in the southern port city of Karachi and Khyber-Pakhtunkhwa.
The attacks prompted UN agencies to withdraw their workers from the campaign. Pakistan is among a handful of countries where polio continues to be endemic.