A loaded Uzi submachine gun was found by police on Monday in a stolen car in south London.
Specialist crime officers found a bag in side the car on Appach Road in Brixton containing the gun, a silencer and ammunition.
Detectives described it as a "significant recovery" helping tackle gang violence in the capital.
Our investigation is in its early stages but we will be working to establish who left the firearm in the vehicle and whether it has been used in any criminality. I would encourage anyone with information about violent crime to contact police or Crimestoppers.