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 reported in the country this year compared to only one in 2021. All the 11 cases were reported from North Waziristan.

The emergency committee under the International Health Regulations (2005) (IHR) on the international spread of poliovirus has recently expressed concern over the outbreak of Wild Polio Virus (WPV) in the North Waziristan district.

It stated that risks to the rest of Pakistan escalated with the ongoing WPV circulation in southern Khyber Pakhtunkhwa (KP).

“The key challenges that hampered progress in southern KP include the complex security situation, specifically in North and South Waziristan, which resulted in inadequate access, missed children and reduced quality of campaigns,” it said. Besides, it noted that community resistance with refusals to vaccination, lack of female frontline workers, and weak health infrastructure and service delivery all posed challenges.

“All WPV cases reported in 2022 are zero dose for routine immunisation, zero dose or under-immunised in supplementary immunisation activities (SIAs), and are from refusal families. Another challenge in South KP is the sub-optimal Routine Immunisation (RI) and progress on strengthening RI in South KP is slow,” it added.