More than 25,000 children were rushed to hospitals in northwest Pakistan after rumours spread that some had suffered reactions to a polio vaccine, officials said Tuesday.
The panic came as health workers were carrying out a three-day vaccination campaign in northwestern Khyber Pakhtunkhwa province, where many residents are already suspicious of the polio vaccine.
Authorities said the fears were unfounded, but declared an emergency at major hospitals in three provincial districts as the panic spread.
An AFP reporter in Peshawar visited two hospitals where he saw thousands of panicked parents arriving in cars, motorcycles and other vehicles with their children.
Most of the parents later told AFP their children exhibited no signs of any problems after being vaccinated, but that they had rushed them to hospital anyway after hearing the rumours.
Qazi Jamil, police chief in the provincial capital Peshawar, told reporters that the rumours began when dozens of children complained of vomiting after they were vaccinated at a private school in a village outside the city on Monday.
After hearing of the complaints, local mosques began using their loudspeakers to warn people against the vaccine.
"The announcements ignited a panic and villagers came out of their homes," Jamil said, adding that a group of some 500 people later set a local health centre on fire in anger. No one is believed to have been injured in the incident.
The panic was compounded by anti-vaccination videos which quickly began circulating on social media.
Hisham Inamullah, provincial health minister, said "around 25,000 kids were taken to hospital".
"Despite all our assurances, parents were worried", Inamullah told reporters Tuesday, adding that just two children were still in hospital but expected to be released soon.
Police are investigating the incident, and authorities said the vaccination campaign would continue until Wednesday.
Polio is endemic in only three countries in the world -- Pakistan, Afghanistan and Nigeria -- although a relatively rare strain was also detected in Papua New Guinea at the end of last year.