Gunmen in Pakistan have killed a health worker who was administering the polio vaccine in a restive tribal region near the Afghan border.
Officials say the attack took place Saturday in Jamrud in the Khyber tribal district.
Local authorities say the assailants left a note with the body warning of similar consequences for anyone who continued the vaccination campaign.
No group has claimed responsibility for the attack.
Militants frequently attack polio workers in Pakistan, accusing them of being Western spies or part of a plot to sterilize Muslims.
The disease is highly infectious and can cause irreversible paralysis.
The Global Eradication Initiative says polio remains endemic in three countries - Afghanistan, Nigeria and Pakistan. The Initiative says until poliovirus transmission is interrupted in these countries, all countries remain at risk of importation of polio.