Mass panic spread after loud bangs in the House of Fraser store, leading to hundreds fleeing the store.
Images have emerged of the windows completely smashed.
Social media users took to Twitter to describe the “frightening” scenes.
One woman wrote: “Craziness in House of Fraser, Oxford Street, never been in a stampede before!”
Some have claimed the window was broken in a robbery.
One person said: @There was legit a stampede of people running, they’re telling us it was a robbery in house of Fraser, the glass is smashed. That’s all I know.”
The road is currently packed with Boxing Day shoppers.
Officers said there is no current evidence of gunfire. One woman has been injured.
The incident comes after a false alarm in November as singer Olly Murs claimed shots were fired in Selfridges.