The incident occurred yesterday in Murgha Kibzai area of Zhob district, sparking fears that they were kidnapped by militants.
The Dawn reported quoting police sources said that five persons were missing.
"The families lost contact with the polio workers since this morning," said the official.
The polio workers and their security escorts were coming back to Zhob when contact with them was lost.
Nobody has so far claimed responsibility for the incident, but it is feared that the missing persons were picked up by militants, who often attack polio workers as they consider polio vaccinations as un-Islamic and a "Western conspiracy".
The incident comes a week after abduction of six Pakistan Telecommunication Corporation Limited workers in the same area.