Authorities say all local residents are safe and accounted for and the fire is under control.
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Firefighters responded to a large blaze at a church in north-west London.
The London Fire Brigade (LFB) said 80 firefighters were sent to St Mark’s church on Hamilton Terrace in St John’s Wood after a call at 23:19 GMT on Thursday.
Videos on social media showed the entire two-storey building alight with black plumes rising from the flames.
LFB said there were no reports of injuries. The cause of the fire, which is now under control, is not yet known.
Households in the area have been advised to keep windows and doors closed.
A local resident described the moment he heard firefighters arrive at the scene after the blaze broke out.
“I got up and looked out my bedroom window and the road outside was full of fire engines,” he told BBC News.
“I thought at the time there must have been some accident further down the road. I just got my coat on, came outside the front door and just noticed the church next door was just ablaze. It’s terrible, the whole church was on fire – smoke everywhere. It’s extremely sad because it’s a very old church and it’s ruined now.”
Another witness described seeing “lots of flames” which became “much bigger before the roof caved in”.
Firefighters are using two 64-metre (209 ft) turntable ladders – equivalent to the highest in service across Europe – to get water on to the building externally.
LFB said investigators would now work to discover the cause of the blaze.
A London Ambulance Service spokesperson said it sent an ambulance crew, a medic in a fast response car and members of its hazardous area response team to the scene.
“The incident is ongoing and we are working with our emergency service colleagues,” the spokesperson added.
Police have asked the public to avoid the area to allow emergency services to work.
About 12 fire engines have been deployed with crews from North Kensington, Paddington and West Hampstead working to put out the flames.
The National Churches Trust lists St Mark’s as a grade II Victorian church, describing it as an “architectural and historical treasure”.
The church, which has links to author Lewis Carroll and Queen Victoria’s son Prince Leopold, is near Abbey Road Studios and Lord’s Cricket Ground.