At 3.05pm on Tuesday, 25 August, officers used tactical contact to stop a vehicle in Hilltop Avenue NW10 as part of a planned operation.
A police firearm was discharged into the tyres of the car.
Four males were arrested on suspicion of firearms offences and kidnap.
Three of the males were treated by LAS prior to be being taken into custody.
No reports of any injuries to officers or members of the public.
The operation is not terror-related.