Police officers were called to the Oxford Street store at just after 1.30pm today.
Nine shoppers were injured in the attack. A man has been arrested.
In a statement, police said: “Police were called to a shop in Oxford Street, W1, on Thursday, 16 July, at 13.39hrs to reports of a disturbance.
“Officers attended along with London Ambulance Service (LAS). It was reported that a man, in his 20s, had been detained by security staff after he sprayed another man with an unknown substance, which causes similar effects to CS gas.
“The man was arrested on suspicion of affray. He has been taken into custody.
“A group of nine members of the public have been treated at the scene for effects of the spray. Enquiries continue.”
A spokesperson for the store said: “The ambulance service are confident it is a non-harmful irritant.
“A few team members and customers were checked over by the ambulance service for irritated nose and throat, with all but one being given the all clear.
“One customer continues to be monitored.”
The spokesperson confirmed the store remained open and was trading as normal.
More to follow…