Oxford Street in central London has been partially closed over fears that a building on fire could collapse.
The fire was on the second floor of the building
About 50 firefighters tackled the blaze, which started just before 1900 BST on Thursday above the New Look store, next door to Marks and Spencer.
Crews were forced to fight the fire from neighbouring buildings because they feared the site could collapse under the intense flames.
Police closed a quarter-mile section between Oxford Circus and Wells Street.
About 150 firefighters fought to bring the blaze under control throughout the night and managed to stop it from spreading to other buildings. But there are now fears the damaged building is unsafe.
Fire crews still do not know what caused the fire
Brendan McAlone, from the London Fire Brigade, said: "Currently we have pulled our crews back, in conjunction with the borough surveyor, because we have some concerns about the building's stability."
Westminster City Council said the quarter-mile exclusion zone would be in place until Saturday morning.
Both Oxford Circus and Tottenham Court Tube stations remain open.
There are no reports of injuries but nearby buildings have been evacuated.
Some 25 retailers - including Muji, Zara and HMV - are unable to trade as a result of the exclusion zone.
But Jace Terrell from the New West End Company said: "We have been assured by tomorrow morning that it will be business as usual and trade will be reopened to shoppers."