Four people were taken to hospital after an advertising board featuring supermodel Kate Moss collapsed on London's busiest shopping street.
The hoarding for fashion store Mango, on Oxford Street, fell at 4.15pm. It was initially feared shoppers had been trapped but emergency services later confirmed that was not the case.
Three women and a man were injured - one with a suspected back injury, while the others suffered minor injuries.
Shocked passers-by posted photographs of the scene on Twitter, one of which showed police officers struggling to hold up the giant picture of Moss.
Witnesses said security staff from nearby shops and passers-by tried to lift the hoarding to free a man trapped underneath.
Two police vans were parked close to the advertising board to prevent another fall, while inspectors from the Health and Safety Executive (HSE) arrived at the scene shortly before 6pm.
The incident caused transport delays for commuters during rush hour, with around a dozen buses forced to stop near the scene.
Part of Oxford Street at the junction with Great Portland Street remained closed while workers attempted to secure the hoarding.
A London Fire Brigade spokesman said: "Three fire engines, four fire rescue units and around 40 firefighters are at the scene. The police and London Ambulance Service are also at the scene.
"It is not thought at this stage that anyone is trapped but around four people are thought to have been injured."
A London Ambulance Service spokeswoman said: "We were called just before 4.15pm to Oxford Street to reports of a collapsed hoarding.
"We sent three ambulance crews, two single responders in cars, a motorcycle responder and a duty officer."
There was no answer at the Mango store on Oxford Street. Moss started modelling for the Spanish retailer earlier this year.
A Scotland Yard spokesman said those injured included a man in his early 60s, a woman in her mid 40s and a 23-year-old woman.
He added: "Police carriers backed onto the hoarding to support it while efforts were made by workmen to secure it.
"It was the kind of hoarding that surrounds a shop when it is being refurbished."