Two policemen, polio worker shot dead during inoculation drive in North Waziristan.

NORTH WAZIRISTAN -- Unidentified assailants shot and killed two police officers assigned to polio vaccination teams and a polio worker in North Waziristan's Datta Khel area on Tuesday, the district's polio emergency response unit said.

The victims were busy with polio vaccinations when they came under attack, an official said, adding that a child was also injured during the incident after he was shot in the leg. He has been moved to the Miran Shah District Headquarter Hospital.

The attackers, on the other hand, managed to escape from the area.

The official added that police and law enforcers immediately reached the spot and began a search operation to trace the attackers.

Later, Deputy Commissioner Shahid Ali Khan also confirmed the incident and the number of casualties. A search operation is underway in the area and further information will be shared in due course, he said.

Prime Minister Shehbaz Sharif said he was "deeply anguished" by the news. The prime minister said he had ordered Interior Minister Rana Sanaullah to conduct a thorough investigation of the incident and submit a report at the next cabinet meeting.

A funeral for the police officers was later held.

The second Sub-National Immunisation Days (SNIDs) campaign this year began on Monday aiming to vaccinate 12.6 million children in all four provinces. Under the campaign, covering 25 very high-risk districts for poliovirus, children under the age of five will be vaccinated. Over 100,000 trained health workers have been engaged in the drive to inoculate children at their doorstep.

Eleven cases of polio have so far been...