A woman has been killed by a falling window frame in central London, after it fell on her as she walked past a construction site in Hanover Square, Mayfair.
The London Evening Standard reported the frame was blown over as the woman, thought to be in her 20s, walked past a new multi-million pound development in the square.
A construction worker on a nearby project said: "It's very windy and they have been putting windows in that building over the past few days."
Another witness described the "horrible scene" saying a four-metre high frame, which had been propped against a wall, had fallen on top of the woman.
One witness told the BBC the woman was eating when she was hit by the window.
People took to Twitter on Thursday afternoon to report there was police tape and a white tent at the scene.
The Evening Standard quoted a London Ambulance Service spokeswoman as saying: “There were extensive efforts to resuscitate the woman but sadly she was pronounced dead at the scene.”
Three London bus routes were diverted following the incident.
A Health and Safety Executive (HSE) spokeswoman said they were aware of the incident and were "making initial inquiries".
Police also attended the scene. A Scotland Yard spokeswoman said: "At this stage it is believed an unknown object hit the woman."
A yellow and white police forensics tent that a witness said contained the woman's body was in place outside 5 Hanover Square.
The south east corner of the square was cordoned off by police and people in blue overalls and hard hats could be seen taking photos and inspecting the area.
The witness, who did not wish to be named, said workers from the building opposite had been sent home.
More than half a dozen police officers were present at the scene.
A woman who works in the Itsu food store opposite the building said she saw a young woman lying on the ground with two paramedics attempting to resuscitate her by pumping her chest.
She said: "I just saw her quickly then I closed my eyes, it was not very nice.
"I could see her legs and them [ambulance staff] pumping her chest. I think it was a young girl but I didn't want to look anymore."
Three workers on a cigarette break outside Vogue House, which also overlooks 5 Hanover Square, said barricades were in place around the building but were removed a few months ago.
One woman said: "We walk past there every day. It's quite scary that it could have been any of us."