A suspected gas explosion today sent panicked workers running for cover in an affluent area of London.
Police said they were called to reports that a gas cylinder had exploded on a Crossrail-linked construction site in Sussex Gardens at around 1.30pm.
A Met spokesman said there were not thought to be any casualties and the incident was apparently not "counter terrorism related".
But extensive road closures were put in place causing grid-lock on many surrounding streets.
Adam Watson, 32, who works for Metalwork Maintenance Services, was on a job nearby when he heard an explosion.
"The bottle went up - it was like a bomb," he said.
"The lads working [on the construction site] tried to deal with it themselves then they ran off.
"Obviously when it's just blown up you're not going to tackle it yourself."
He added he thought the fire was sparked by construction workers cutting metal and said: "At one point the bushes were on fire."
At the scene, police cordoned off a large area to address fears the flames could spark secondary explosions.
On Twitter, passers-by commented on the incident.
Rodney Buckingham (@roddersbuck) wrote: "Something bad happened in Sussex gardens london, could be a crossrail problem, hope everyone's ok."
Paul Charalambous (@PaulStylotel) tweeted: "Sussex Gardens closed completely at the junction of London Street due to water mains explosion on site of current works #paddington."
And David Hornby (@DavidHornbyUK) added: "Much of #Paddington sealed off after reports of gas explosion in Sussex Gardens #LondonW2."
The construction site, managed by Thames Water, relates to utilities work being undertaken as part of the Crossrail programme.
“We’re very sorry to anyone inconvenienced by the disruption around Sussex Gardens today," said a Thames Water spokeswomen.
"Our teams were working on a project to strengthen water pipes when a small fire, caused by a gas canister, broke out. We’ll carry out a full investigation into what happened."
The water supplier added that firefighters were waiting for gas cannisters to cool before reopening the road - which was expected to happen later on Thursday evening.
