Panic descended on Oxford Street during the Boxing Day sales after shoppers mistakenly thought they heard gunfire, leaving one woman injured when a window smashed.
The Metropolitan Police said they were called to the bustling high street on one of its busiest days of the year to reports of shots at 4.50pm.
Armed police were scrambled to the area alongside regular officers but no trace of the apparent gunshots, nor signs of any criminal offence, were found.
The chaos appears to have centred on the House of Fraser department store, where one large window pane facing on to the pavement was broken.
A woman suffered non-life threatening injuries in a fall linked to the smash, which it is understood she did not cause.
Passerby Julia Dixon wrote on Twitter: “Craziness in House of Fraser, Oxford Street, never been in a stampede before!”
It is the second time in recent weeks that armed police rushed to Oxford Street following a gunshot scare.
On November 24 there was mass panic and confusion as rumours of a gunman began circulating. Several people were injured.
No evidence of any shooting was located by police.
Trouble also hit one of the capital’s other main retail hotspots, the Westfield centre in Stratford, east London, where seven arrests were made following a disturbance.
Police were called at 2.34pm after reports that several people were bringing disorder to the shopping centre.
Officers dispersed the suspects and arrested seven individuals for “a variety of offences”, while several knives were recovered.
Two police officers were treated in hospital for minor injuries suffered during the arrests.
A Section 60 order was placed on the shopping centre covering a 500-metre radius until 10.30pm, the Newham Borough arm of the Metropolitan Police said on Twitter.
The order gives officers extra powers in the designated area to prevent the occurrence of further disruption.
Additional patrols were sent to the area, the force added.