"A group of armed Maoists packed dynamites inside the Nawadih Middle School and triggered the blast, damaging its three rooms," said Superintendent of Police, D B Sharma.
Moreover, they set rail office on fire at Banshipur station in Lakhisarai district after taking eight officials hostages and blew up a block office in neighbouring Munger.
CPI (Maoists) observed a 48-hour bandh to protest the Centre efforts to subjugate them by force.
The police tightened security including, patrolling of railway tracks at several places in naxal-pockets.
However, the 48 hours bandh disrupted the normal life and transport.
But the bandh did not affect the urban areas.