Thames Valley Police is appealing for witnesses after a driver was threatened with a firearm while travelling on the M4.
The victim, a 37-year-old man was driving westbound on the M4 between junction 4B and junction 10 on Wednesday the 2nd of January at about 5.30pm.
While he was in traffic, he pulled alongside a black Audi A8 with tinted rear windows.
On at least three occasions, the driver of the Audi pointed a firearm at the victim from within the vehicle.
The victim eventually drove away from the offender and was unhurt.
A 36-year-old man from Swindon has been arrested on suspicion of being in possession of an imitation firearm with intent to cause fear of violence.
He has been released under investigation.
Investigating officer, Detective Constable Rachel Kluger, based at Slough police station, said: “We are carrying out an investigation into this incident, and have made an arrest and recovered an imitation firearm.
“We’d like to speak to anyone who witnessed this incident or who was travelling on this section of the M4 between about 5.20pm and 6.20pm.
“We would also be especially keen to talk to anyone who has dash-cam footage which shows this incident or others like it.
“If you have any information, please call the Thames Valley Police non-emergency number on 101, quoting reference 43190001744.”