Cases have been registered against unknown attackers involved in the killing of polio vaccinators but no arrest has been made yet, officials said on Thursday.
In Charsadda, the cases were registered in Nasta, Sudheri and Butgram police station.
The polio campaign has been suspended in the province after killing of polio vaccinators that included a female volunteer also.
The cases have also been registered in Karachi where four health workers were killed on Tuesday.
