The incident occurred while the teen was waiting to be interrogated.
A 16-year-old boy accused of a minor theft was shot when a cop's revolver allegedly went off at a police station near Chennai.
The teenager was reportedly waiting to be interrogated when the incident took place. He has been admitted to a private hospital where he has had a surgery on his neck.
The police claim it was an accidental shooting; the boy was injured when a loaded revolver, which an Inspector was cleaning, went off.
"We have ordered an inquiry by the Revenue Divisional Officer as the case is against the police," a senior police officer told NDTV.
The boy's family suspects the police are lying.
Child rights activist say the police violated the Juvenile Justice Act, which says minors cannot be brought to the police station for questioning, no matter what their crime is.
"We demand a thorough probe and stringent action against the police who are responsible," Mr A Narayanan, an activist, told NDTV.