Piccadilly Circus in central London has been closed after an explosion which resulted in a lorry catching fire.
Metropolitan Police officers and London Fire Brigade (LFB) attended the scene at the Piccadilly junction with Sackville Street just before 11pm yesterday.
A spokesperson for the Met said: "At this early stage, the fire is believed to have been caused by an electrical fault beneath a manhole cover."
The fire was brought under control and a spokeswoman for LFB said crews had a water jet at the scene as they awaited the arrival of the electrical authorities.
There were no reported injuries and no arrests.
Witness Jon Hornbuckle tweeted to say there had been numerous explosions and thick black smoke.
"That was scary, I was 10 steps away and then BANG," he wrote.
The road reopened shortly before 4am, a spokesman for the Met said.
In February, 50 people were evacuated from a street in north London after a pavement burst into flames.
In April last year, a fireball burst from a pavement on a busy street in central London, narrowly missing a passer-by standing just yards away.
The explosion on Pimlico Road, in central London, was said to have shaken nearby buildings and left a gaping crater at the side of the road.
Last year, figures obtained by BBC London showed reported incidents of underground explosions in the capital more than tripled between 2011 and 2012.
A spokesman for UK Power Networks said: "At approximately 11pm last night, UK Power Networks received a report of an incident involving a fire from a cable pit in the Piccadilly area of central London.
"Our engineers were quickly on site to assist the emergency services in making the area safe and a full investigation is being carried out as to the cause of the incident."