Parts of the City of London were evacuated following concerns over a suspicious vehicle outside the building known as the Gherkin on 28 November.
Armed police were seen in the area with cars and pedestrians blocked from entering.
In a statement, police said: "We are currently in attendance in St Mary Axe (EC3) following a report of a suspicious vehicle parked on the street. Road closures are currently in place in the surrounding area and people are advised to find different routes."
Several people have taken to Twitter revealing that they are in lockdown, including some who have been trapped inside the Gherkin while the police carry out their checks.
A specialist robot was photographed approaching the silver Ford Focus which is parked on St Mary Axe, just off Leadenhall Street.
Police were seen soon afterwards entering the vehicle with reports of a controlled explosion taking place.
The location would normally be busy with business people and tourists during the lunchtime rush in one of the busiest parts of the city.
Members of the public were told to stay indoors with officer workers locked in their buildings while checks were carried out.
At around 12:45pm, the situation appeared to return to normal with the apparent threat averted.
City of London Police later confirmed that the situation had been resolved and the car was no longer deemed as suspicious, but the driver of the vehicle was arrested for the possession of false identity documents.