Hundreds of school children in Pakistan were taken to hospitals Monday complaining of nausea and vomiting after being given polio vaccinations, officials said.
They said angry family members responded by storming a local health facility in Peshawar and setting it ablaze.
The incident deals another blow to efforts to eradicate the disease, which have been hindered by widespread distrust in some areas. Islamic extremists have targeted polio workers and stoked conspiracy theories that the vaccinations are part of a Western plot to sterilize Muslims.
Pakistan, neighboring Afghanistan and Nigeria are the only three countries where polio is still endemic.