Two killed and two others were critically injured in a blast in a playground in Bihar's Khagaria district near the Gogri police station area.
A police official on Monday said three children were playing in the Bhagwan High School ground on Sunday evening.
While playing, all of them hid behind some bushes and started hitting an explosive with a stick mistaking it for a ball. One of the children picked up the explosive following which it exploded.
Khagaria Deputy Superintendent of Police Manoj Kumar said with the help of the local people the three injured children were taken to the Sadar hospital for treatment. But nine-year-old Mohammad Kurban died on the way to the hospital.
Kumar said some people may have hidden the bomb in the bushes to carry out an attack. The police is conducting a search operation after sealing the entire area and a hunt is on for the culprits.