The incident occurred at around midnight yesterday when the inmates, aged between 15 and 17, managed to break the main door (grill) lock of the juvenile home run by an NGO.
When the watchman tried to stop them, they pushed him aside and ran away, L B Nagar Police Inspector P Kasi Reddy told PTI.
"The watchman, who is an old man, suffered minor injuries during the incident," Reddy said.
Following a complaint, a case under IPC sections 224 (resistance or obstruction by a person to his lawful apprehension) and 324 (voluntarily causing hurt by dangerous weapons or means) was registered, police said.