Two young men and a teenager were arrested on suspicion of carrying weapons in West Drayton, Hillingdon, on Sunday afternoon (January 21).
The group's car was stopped by armed police in Bell Avenue near to the junction with Thornton Avenue at around 3pm.
Armed officers carried out a search of the area after being called to reports of three men in a vehicle in possession of knives and a firearm.
The 17, 18 and 26-year-old in the car were all arrested at the scene on suspicion of being in possession of a firearm, with one of them also arrested on suspicion of being in possession of an offensive weapon.
No firearm was found but a knife was recovered at the scene.
The three were taken to a west London police station where they remain in custody.
The arrests were made two days after a 37-year-old man was stabbed in the back behind West Drayton railway station on Friday (January 19).
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