PESHAWAR, Pakistan — A devastating roadside explosion targeted a vehicle transporting police officers who were tasked with guarding polio workers in the troubled northwest region of Pakistan on Tuesday. The blast resulted in the deaths of three officers and left two others injured, as reported by local law enforcement.

The incident unfolded in the Dera Ismail Khan district within Khyber Pakhtunkhwa province, happening while the officers were on their way back to their respective stations, according to police officer Nasir Khan.

As of now, no group has claimed responsibility for this attack, which followed closely after a shooting incident in Karak—a city located in the same province—where unidentified assailants opened fire on police who were protecting polio workers. That earlier attack resulted in one police officer’s death and injuries to a health worker.

This surge in violence coincides with Pakistan launching its final nationwide polio vaccination initiative for the year, with a goal of immunizing 45 million children. The World Health Organization has stated that both Pakistan and Afghanistan are the last two nations where this potentially deadly poliovirus has not been fully eradicated.

Since the beginning of the year, Pakistan has recorded 63 confirmed cases of polio, and the current vaccination campaign is set to run until December 22.

In these volatile times, militants frequently target police and health personnel during polio vaccination efforts. It has been documented that over 200 polio workers and the police assigned for their protection have lost their lives since the 1990s, as confirmed by health officials and governmental sources.