Senior police official Kripashankar Singh says the children had wandered out of Mother India Public School in Kaushambi, 180 km southeast of Lucknow, during a lunch break and entered an abandoned house where the incident occurred.  Lucknow is the capital of Uttar Pradesh state.

He said the injured children were sent to a hospital. Singh says police is investigating the cause of Tuesday's blast, which may have been a crude explosive device hidden in the house.