Prasad succumbed during treatment at the Patna Medical College and Hospital (PMCH), Nalanda's Superintendent of Police (SP) Sidharth Mohan Jain told PTI.
A post-mortem was being carried out on the body to ascertain exact cause of the DPS official's death, he said.
TV footage showed that the Director of DPS branch of school located near Nirpur village was mercilessly beaten up with lathis by a mob who held him responsible for the death of two students of the prestigious school.
The badly battered DPS official was taken by a police team led by the DSP (Law and Order) Sanjay Kumar to Sadar hospital at Biharsharif where the attending doctors referred him to PMCH at Patna, the SP said.
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He said strict action will be taken against the guilty persons.
An FIR was lodged against those people responsible for the assault on the DPS official, Jain said.
Earlier in the day, the bodies of two students, aged around 7-8 years, of the prestigious residential public school were recovered from a waterbody.
The mob also targeted some policemen who had arrived there to probe the death of two students and pelted stones on the cops, injuring six including Nalanda police station in-charge Sunil Kumar, the SP said.