Chhapra, July 2: Two children sustained serious injuries this morning when a bomb hidden in a bag on the campus of Children Delight School at Paharpur under Garkha block, 6km from the district headquarters, went off.

Sources said around 7.30pm, two boys, Abhimanyu and Pintu, aged between 10 and 11, had taken their buffalos for grazing.

They entered the school campus to quench their thirst. Before that, they went to urinate and suddenly stepped on a bag containing a bomb.

The explosion was so powerful that the urinal collapsed and the asbestos roof was blown off. Both of them sustained serious injuries.

They were rushed to Chhapra Sadar hospital from where they were referred to Patna Medical College and Hospital in a critical condition.

One of the injured, Pinti, said when they went to urinate, he stepped on the bag by mistake and the bomb exploded.

The school is an extended branch of Children Delight School that runs at Chhapra and is abandoned.

Sources said following three attempts to restart the school, it was slated to be inaugurated today. The villagers suspected it to be the handiwork of some rival schools.

However, superintendent of police A.K. Satyarthi said the bomb was a country-made one sutli.

He denied that it could the work of Naxalites but of people who did not want the school to run. He said that the police are investigating the case from all angles.