Holborn Underground station in London's West End was evacuated after smoke began to fill the platform, The Telegraph reported. 
Passengers reported seeing a "flash" before a "loud bang" at the Tube station at about 9:00 am on Tuesday.
Transport for London (TfL) said the incident related to a faulty train at Holborn, which is served by Central and Piccadilly line services. 
Trains were being held at the station while the train was inspected.
At about 10:00 am, British Transport Police said it was "working to reopen" the station after a "defective train caused an evacuation". 
A short time later, TfL said the station was fully reopened and trains were stopping again as normal.

Source: Mena