© ReutersAn explosion sends a fireball into the air
Fifteen engines and 100 firefighters were sent to the south east London station, where the fire had started in garages in the arches of the railway station.
Videos from the scene showed explosions sending fireballs out of the unit (below), with people having to evacuate the area. One image captured on social media showed a police officer carrying two children from the station.
Six people including a police officer were injured in the fire, which started just before 2pm. They were treated by paramedics for smoke inhalation and one was taken to hospital.
The London Fire Brigade (LFB) reported that the fire spread quickly, setting two other industrial units under the arches alight as well as four cars and a telephone box.
Huge plumes of smoke could be seen billowing up from the station and the garage below.
"Officers are supporting LFB in Elephant and Castle. "There are significant road closures in place and the public are advised to avoid the area. "The incident is not believed to be terror related."
Officers at the scene said the station has been fully evacuated along with the nearby Strata residential building.
Residents were seen on the streets near the cordon with their pets having been evacuated and the fire was extinguished by 4pm.
What caused the fire?
"The source of the fire is under investigation at the moment. We will be working with the police and with the fire investigation team, but at the moment that is not known.
"There's no concern at the moment that anyone is missing. The fire is being brought under control as we speak.
"There's a couple of cylinders, or at least one cylinder, that has been identified in there, which will be in the process of cooling before we can declare it safe and move out.
Witness accounts and reaction to the fire
Sara Scarpa, 25, lives in nearby apartment building Hurlock Heights and said smoke and the noise of the explosion had reached her window.
"We opened the window for a sec as you could hear people shouting, and we smelt something very very strong," she said.
"The smoke (was) dying down a little... we heard an explosion and now it started again."
Alex Leckie, 30, assistant manager at Tupi, said: "The entire building was evacuated, we began to smell smoke and the store owner went to check, we saw smoke billowing out and what I'm told is the mechanics were on fire, the smoke pillar started enveloping the apartment blocks as well and we kept hearing intermittent bangs.
"I heard the police come and I thought there was an accident nearby, but then they started blocking the road off. I then came outside for a cigarette and saw all the black smoke," he said.
"I was really surprised to see it and a bit scared. They haven't told us anything. The smell was awful. It smelt like a burning electrical cable smell."
Abdullah Safi, 21, who works at Chatkhara restaurant, was on his way to the Sainsbury's nearby to the station when he saw the flames.
He said: "I saw so much smoke. The fire was burning so high, about 50ft, so I started recording on my phone.
"Suddenly there was a big explosion, so I ran away. I ran back to my restaurant. I wasn't hurt or anything. I've never felt so much heat and so much smoke at once.
"I've never seen something that big - I was scared. And it exploded twice."
Mayor of London Sadiq Khan said a member of the public and a police officer were being treated for smoke inhalation.
Network Rail said initially trains would continue to travel through the station, but will not stop there.
Comment: Other fires and explosions in the news recently: