London fire LIVE: Massive blaze causes chaos as 100 firefighters rush to scene

The London Fire Brigade added: "An unknown number of gas cylinders at the site are believed to have exploded during the early stages of the incident.

"Firefighters have safely removed two further cylinders and cooled them to an ambient temperature, as gas cylinders can explode when exposed to heat."

Pictures show fire crews at the scene while smoke billows into the air.

The London Fire Brigade said: "Fifteen fire engines and around 100 firefighters were called to a fire near Roxeth Green Avenue in South Harrow.

"The fire occurred at a range of four railway arches, housing businesses including vehicle workshops and other commercial uses.

"The properties have been severely damaged by fire.

"Firefighters have worked hard to bring the fire under control but the Brigade is likely to maintain a significance presence on scene for several more hours."

Commuters in London face lengthy delays this morning (July 4) due to a huge fire.

The blaze broke out under the London Underground Piccadilly line tracks in South Harrow. Fire crews were called to the scene at around 1.15am.

Welcome to our live coverage of this breaking news incident. The Daily Express team will be bringing you live updates after a fire in London sparked travel chaos during rush hour.

More to follow...