A man has died after being hit by a large metal sign that fell from a William Hill shop.
The man, believed to be in his 20s, was treated at the scene in Camden, north London, on Monday afternoon before being taken to hospital, where medical staff were unable to save him.
He has not yet been named.
"Every effort was made to resuscitate him at the scene and on the way to University College Hospital," a London Ambulance Service spokeswoman said.
The 30ft sign, which had covered the length of the betting shop, was seen on the pavement. Police erected a forensic tent to cover the scene and taped off the surrounding area.
Ioana Nita, 21, was working at a nearby restaurant when she heard a "very loud noise".
"Me and a colleague went outside and saw the guy lying on the floor," she said.
"Five guys picked up the sign and it was put on the side. His hands were covered in blood and he wasn't moving.
"Lots of people were in a circle around him, then the ambulance arrived and they were trying to get him back to life, pressing on his heart."
She added: "I just want to go home and cry. I don't know how that can happen. The sign is huge. Everyone said he was just walking past the shop."
Ken Osbourne, 28, who works at the nearby Woody Grill restaurant, said: "I saw the guy lying down in the road, covered in blood.
"Hundreds of people walk past here every day. It could've been me or any one of them."
Health and safety investigators entered a flat above the shop to take photographs of the sign. Flowers have been left at the scene.
A William Hill spokeswoman said: "There is an urgent investigation under way and we are still establishing facts and liaising with authorities.
"As such, we don't have a comment to make at this time."