A 17-year-old boy went into cardiac arrest when he was tasered by police officers.
The teenager is in a serious but stable condition in hospital following the incident in Coventry, West Midlands Police has said.
Four oher youths, three aged 17 and one 13-year-old, were also arrested after officers were called to reports of a disturbance in the Canley area of the city last night, just after 9.30pm.
The police force said the 17-year-old was tasered in an effort to detain him but he immediately required CPR as he went into cardiac arrest.
The four other youths were arrested on suspicion of violent disorder and assaulting a police officer.
Two male police officers received minor injuries which did not require hospital treatment, and a patrol car had its windscreen smashed.
The incident has been referred by the force to the Independent Office for Police Conduct.