A large fire at a Greenwich motorcycle repair shop, believed to contain gas cylinders, caused the Blackwall Tunnel's closure for three hours this morning as smoke was sent billowing across the area.
Fire crews were called out to the blaze at All Bike Engineering in Peterboat Close at around 6am this morning.
The whole building was alight and it was believed the shop contained gas cylinders which could explode from the heat.
Six fire engines attended the incident with around 35 fire fighters involved.
Their first priority was to bring the fire under control and then cool down the cylinders.
A brigade spokesman said: "The cylinder involved in the Blackwall workshop blaze is being cooled and crews are still on the scene putting out remaining pockets of fire."
An exclusion zone was set up around the fire and businesses on the same industrial estate were evacuated.
Josh Williams, 24, was sent home from neighbouring unit Datashred. He said: "I know they've got cylinders there because they're always outside welding.
"We actually saw the flames coming out of the front door.
"It looks like the building's going to have to be torn down straight after."
He went on: "The wind did change and the smoke started blowing over to us and we had to quickly go inside so we didn't breathe it in."
Smoke was blown across the area, resulting in the closure of the Blackwall Tunnel Approach northbound and southbound.
The Blackwall Tunnel was closed for three hours and there are still severe delays and queueing traffic in the surrounding area.
Residents near the fire were advised to keep their doors and windows closed due to the smoke in the area.
The brigade said it expects to be on site until tomorrow morning whilst firefighters spray cool water onto the cylinders to cool them down and make them safe.
At its height the fire caused heavy traffic around the Blackwall Tunnel but the road is now open again in both directions.
No injuries were reported but local residents were advised to close doors and windows due to heavy smoke from the fire.
Station manager Tim Frost said: "At the height of the incident the whole of the repair workshop was alight. There were a number of gas cylinders inside the premises and fire crews worked to cool them down, as some cylinders can explode when exposed to heat."
The cause of the fire is under investigation by the brigade's fire investigation team.