A tree surgeon has died after he is thought to have injured himself with a chainsaw.
The man, believed to be in his 30s, suffered a neck injury during the incident in Bermondsey, south-east London, near a school on Wednesday morning.
One witness tweeted that he saw "a lot of blood" in the area following the accident at Banyard Road shortly after 11am.
Another man, Charlie Brenland said he saw police cordon off the road, adding: "Witnesses and the police said there had been an accident with a worker on one of the trees.
"Someone there said one of the tree surgeons had an accident with a chainsaw."
A spokesman for the Met said: "This is believed to be a workplace accident and the Health and Safety Executive (HSE) will be informed in due course."
In a statement the London Ambulance Service said: "We sent an ambulance crew, a single responder in a car, a paramedic on a motorcycle, an incident response officer and our Hazardous Area Response Team (HART) to the scene. We also dispatched London's Air Ambulance.
"Sadly, despite the extensive efforts of our crews, a patient died at the scene."
A spokesman for the HSE said it was "aware and assisting the Metropolitan Police in their investigation and HSE inspectors are attending the site".