According the sources, the four children became unconscious after being vaccinated and didn't recover thereafter.
A magisterial inquiry has also been ordered into the incident and the vaccination programme will remain suspended till the investigation is completed.
"We will take strict action if it is found that these were wrongly administered, we have collected samples of these dozes and have sent them for testing to find out if they were genuine or spurious," said district magistrate of Lucknow.
Pediatricians said that an immediate inquiry should begin and the entire batch be pulled out of the programme to establish the cause of death or else the vaccination programme which is doing poorly in states like Uttar Pradesh can suffer a serious setback.
"Prima facie it seems that the incident occurred due to spurious vaccine. This is a very serious incident. We will take appropriate action. Compensation of Rs 50,000 will be given to the families," said DM & CMO Anil Sagar.