Ten fire engines and more than 70 firefighters and officers were called to a fire in a basement in Sanctuary Street, Southwark.
Part of the basement at a publishing warehouse was damaged by fire.
Station Manager Nicola Lown, who was at the scene, said: "Basement fires can be quite hazardous due to the heat and cramped conditions. Firefighter crews spent about 20 minutes at a time inside the basement tackling the fire, and were then replaced by the next crew.
“Firefighters worked really hard to bring the fire under control quickly, and once the fire was out they ventilated the building and made it safe.”
The Brigade was called at 1031 and the fire was under control at 1202. Fire crews from Lambeth, Dowgate, Old Kent Road, Shadwell and other surrounding fire stations were called to the scene.
The cause of the fire is currently unknown.