Armed gunmen on Tuesday shot dead a police officer guarding a team of polio vaccine handlers in northwestern Pakistan, according to local officials.

The attack took place in Karak, a remote town in Khyber Pakhtunkhwa province, on the second day of a five-day national polio immunization drive. According to official figures, Karak and adjoining areas recorded 15 of province's 22 cases polio cases last year.

"Two gunmen came on a motorcycle and attacked our colleague Junaid Ullah while he was escorting the polio team. They opened fire on the van carrying polio workers," Muhammad Ishaq Khan, a police official in Karak, told DW.

"Police teams have launched an operation to catch the attackers. The polio vaccination campaign has been temporarily halted; we will resume it in the area tomorrow," he added.

Read more: Deutsche Welle