Staff were evacuated from the Big Yellow depot in Barking last night after a battery caught alight in one of its self-storage units.
Part of the ground floor of the four-storey warehouse in Hertford Road was damaged by the blaze.
Emergency services were called just before 6.30pm on Tuesday - February 8 - after a member of staff raised the alarm.
About 60 firefighters using eight engines had the fire under control within an hour.
London Fire Brigade (LFB) station commander Paul Easton, who was at the scene, said: "Fortunately all the staff who were in the building were able to get out and there were no reports of any injuries.
"Firefighters wearing breathing apparatus extinguished the fire and then used breaking-in gear to force entry into neighbouring units to prevent any further fire spread."
It's believed the failure of a lithium-ion battery caused the fire.
Adrian Lee, operations director at Big Yellow self-storage explained that while crews managed to confine the fire to just one room, a further 10 have been affected by smoke and water damage.
"To put it into context, there was a small fire in one of the rooms inside the store, which has about 900 rooms," he said.
Adrian commended the LFB for reacting "fast and hard" to the blaze, actions which ensured it was under control quickly.
He added: "The good news is it's all back to normal and the store is up and trading as normal today."
The operations director confirmed that every customer has to be insured, with those affected to bring claims.
Adrian is grateful that, despite some clear consequence, the fire remained "quite a small incident".
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