An 18-year-old was in hospital after being shot by an armed officer during a police operation, according to Scotland Yard.
The teenager - whose injuries are not thought to be life threatening - was shot once as he sat in a car in Vicarage Farm Road, Hounslow, west London, just after 2.30am.
A Scotland Yard spokesman said no information was available yet on whether any of the youths were armed, or the reason for the police action.
He said: "As part of a planned police operation, a motor vehicle was approached by armed officers.
"One shot was discharged and an occupant of the car was injured."
The injured youth, who is of Asian origin, was taken to an unnamed hospital.
Two other men in the car, both aged 19, one of whom was black and one of Chinese origin, were arrested and taken to a police station in south London.
An investigation into the incident is under way and the Police Complaints Authority have been informed, the spokesman said.
No officers were thought to have been injured, he added.
The independent Police Complaints authority has agreed to supervise an investigation into an incident, and an external investigating officer be appointed.Reuse content