Armed men have opened fire on polio workers in three separate attacks in northwest Pakistan, seriously wounding one, the latest victim in a string of attacks that left six female health workers dead since Monday.
Wednesday's victim was part of a team of four or five men administering polio vaccinations when gunmen opened fire on the group, said a doctor at Lady Reading Hospital where the man was being treated. He remains in a critical condition.
Senior police official Asif Iqbal confirmed the attack and said police were investigating the motive and who was behind it.
Two other polio teams were targeted in similar attacks in the towns of Nowshera and Charsadda, police said, but the health workers escaped unharmed.
One passerby was slightly injured in Nowshera.
On Monday and Tuesday, six female health workers were killed in attacks in the southern port city of Karachi and Peshawar. The youngest was 17-years-old.
Pakistan, one of only three countries in the world where polio remains endemic, launched a UN-backed three-day nationwide vaccination campaign on Monday.
There has been no claim of responsibility for the polio worker attacks, which authorities say they were co-ordinated and occurred at the same time in different parts of the country.
Senior police officer Shahid Hayat blamed "militants who issued a fatwa against polio vaccination in the past" for the killings.
In June the Taliban banned immunisations in the tribal region of Waziristan, condemning the polio campaign as a cover for espionage.
After Tuesday's attacks, the government of Sindh province, of which Karachi is capital, halted the immunisation drive, and an official said the Khyber Pakhtunkhwa government would have no choice but to follow suit.
"We are holding an emergency meeting with our donors and we have no option but to postpone the vaccination campaign for the time being. We will formally announce it after the meeting," Janbaz Afridi, doctor in charge of the immunisation campaign in Khyber Pakhtunkhwa province, said.
Efforts to tackle the highly infectious disease in Pakistan have been hampered over the years by local suspicion about vaccination.
All of the victims were Pakistanis who were working with a UN-backed programme to eradicate polio, a disease that attacks the nervous system and can cause permanent paralysis within hours of infection.
The disease has been wiped out in all but a handful of countries. At least 35 children in Pakistan have been infected this year.