Hotels and businesses in part of London's West End have been evacuated following the discovery of a gas leak, police said.
Emergency services were called to the Strand in the heart of the capital's tourist district shortly after 2am.
There were reports of revellers being ordered to leave a popular nightclub close to Charing Cross station after the alarm was raised.
One tweeted: "We were just in Heaven and the whole club got evacuated wtffff is happening."
The discovery of a gas leak forced road closures in the area, threatening to cause disruption for the morning rush hour.
The Metropolitan Police tweeted:"Due to gas leak in the #Strand, WC2 businesses and hotels are being evacuated as a precaution.
"Officers are working with the @nationalgriduk and partner agencies.
"A cordon and road closures are in place as a precaution and members of the public/motorists are advised to avoid the area at this time."