Peshawar Two policemen escorting a team of polio workers were killed by unidentified gunmen on Wednesday in Pakistan's Khyber Pakhtunkhwa province, police said.
The KP province has launched an anti-polio drive from December 16.
According to police, unidentified gunmen shot dead two policemen while they were escorting a team of polio workers in Dir district of the province.
The assailants managed to flee from the scene after the incident, they said, adding that a search is on to nab them. Pakistan is one of the three countries, along with Afghanistan and Nigeria, where polio is still endemic.
However, attempts to eradicate the crippling disease in Pakistan have been seriously hampered by deadly targeting of vaccination teams in recent years by militants, who oppose the drives, claiming that the polio drops cause infertility.
Attacks on immunisation teams have claimed 68 lives since December 2012.