About 1,450 people have been evacuated from a nearby hotel and nightclub after a gas main ruptured in central London.
Londons's Charing Cross and Waterloo East stations were shut, with services diverted into Victoria, Cannon Street and Blackfriars after the incident.
Waterloo East station was also closed because trains were unable to turn around on that stretch of a line before reaching Charing Cross, reported the Guardian.
London Fire Brigade (LFB) said it was called to the scene after high levels of natural gas were detected at the scene in Craven Street near Charing Cross station.
As reported, the police cordon in the area may not be lifted for another four to five hours.
One witness described "chaos" at the Heaven nightclub, beneath Charing Cross station, as doormen ordered visitors to leave after the alarm was raised, reported the Guardian.
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One clubber tweeted, "Evacuated from heaven because of a gas leak wow. Literally chaos. Crush on the stairs. Security being knocked aside."
The Strand was entirely closed and a 150-metre cordon put in place, while the National Grid engineers tried to isolate the leak.
According to Sky News, two fire engines, 20 fire rescue units and 20 firefighters are at the scene.
"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, a London Fire Brigade spokesman said.