The officers were providing security for the health workers, who were administering vaccines in the Khyber Pakhtunkhwa region, Dawn News reported.
Vaccination workers have become a target for militants, who see the activity as cover of espionage and who believe the drops make children infertile.
Pakistan, along with Nigeria and Afghanistan, are the only countries where polio remains endemic. The World Health Organization says Pakistan had 91 cases of polio in 2013, an increase from 58 in 2012.
Susan Sarandon 'very excited' about daughter's pregnancy
Interpol investigating stolen passports on missing flight