More than 1,000 people have been evacuated from a nightclub and a hotel in London's West End after a gas leak was discovered on Craven Street, just off Strand.
Approximately 1,450 people were moved away, London Fire Brigade said.
Emergency services were called to the heart of the capital's tourist district shortly after 02:00 BST.
Roads in the area have been closed and Charing Cross station, threatening to cause rush hour disruption, reports BBC.
The Metropolitan Police said it was working with the fire service and partner agencies to deal with the leak.
A ruptured gas main has been detected by firefighters, the brigade said. There were no injuries reported.
A spokesman said: "We are assisting police on the Strand after a ruptured gas main was discovered using detection equipment and high levels of natural gas were detected in the atmosphere."
"We do not know the cause of the gas leak at this stage. It is ongoing and engineers are down at the scene trying to isolate the leak. There are still high readings of natural gas in the area."
"We are working to sort it out as quickly as possible."
A rest centre has been set up for affected residents at the Queen Mother's Sport Centre in Vauxhall Bridge Road, Westminster Council said.