After being alerted to two unattended vehicles near the new U.S. embassy in Wandsworth, south-west London, the police carried out a controlled explosion.
The police used a bomb disposal robot for the controlled explosion of a red van parked next to the unopened building on Ponton Road at 5.37pm on Wednesday, The Guardian reports.
The ambulance and fire service vehicles and cordons were in place.
The Metropolitan police said the vehicles were not suspicious. The roads were shut down at the beginning, which the police said would be opened soon.