Patna, June 9: Tension gripped Beur Central Jail this morning after three undertrials beat up another inmate, Dukhan Mahto, for allegedly informing the prison administration about prisoners keeping cellphones with them.

The incident took place at the Ganga Sector-5 ward of the prison around 11.30am, sources in the jail said.

Beur jail superintendent Shailendra Priyadarshi told The Telegraph that Mahto suffered minor injuries and has been sent to his ward following necessary medication. He added that the assailants, Vijay, Pappu and Hullar Paswan, have been locked up in the high security Gol Ghar of the jail.