Approximately four marked Thames Valley Police cars and an unmarked car were spotted in Eldon Road at around 8.30pm today (Friday, December 19).
A photo shows a man in handcuffs after being accosted by officers.
Drivers heading south needed to swerve around the police vehicles to continue their journeys.
Traffic remains slower than usual in Eldon Road between its junctions with Kings Road and Eldon Terrace.
Thames Valley Police will be contacted for a statement.
More will follow tomorrow (Saturday, December 20).
