A female anti-polio immunisation campaign worker was gunned down and another injured on Thursday in Balochistan's Chaman.

Assistant Commissioner Syed Sami Agha told reporters that unidentified suspects opened fire at the immunisation team in Sultan Zai, a city near the shared border with Afghanistan. The suspects managed to flee after the shooting.

He said both victims were shifted to District Headquarters Hospital.

Take a look: Health: The battle against polio is still on

The vaccination campaign in the area has been suspended and security forces cordoned off the attack site and launched a search operation for the assailants. More than 2.5 million children in Balochistan were to be administered the anti-polio vaccine during the campaign.

As many as 10,356 teams were deployed to vaccinate children. Apart from the 8,829 mobile teams, 951 fixed points and 576 transit points had also been set up all over Balochistan to ensure that all children are administered anti-polio drops.

Several polio workers in Balochistan and other parts of the country have been killed by militants, while apprehensive parents routinely refuse to have their children inoculated during door-to-door campaigns. On April 8, a union council polio officer associated with the World Health Organisation was shot dead in Ghazi Baig area of Haleemzai tehsil in Mohmand tribal district.

The latest attack targeting an immunisation team comes days after anti-polio panic spread across Peshawar and other parts of Khyber Pakhtunkhwa amid reports that some 75 students at a school in Peshawar's Badhber area had been admitted to a hospital with complaints of nausea and headaches after being vaccinated.

Following the panic, a police officer deployed at a Bannu basic health unit for security of immunisation workers during a province-wide drive was gunned down by unknown assailants while on his way to work on April 23.

Last year, 12 cases of wild poliovirus were reported in the country — five from Bajaur, three from Dukki, and one each from Charsadda, Lakki Marwat, Khyber and Gadap. The data indicates a 97 per cent decrease in the number of annual polio cases from the high tally of 306 reported in 2014.