British police on Sunday said they had shot a man in south London, after at least two people were stabbed in a suspected "terrorist-related" incident.
Police later said the man had died as a witness spoke of seeing a man in Streatham "with a machete and silver canisters on his chest".
"We can confirm that the man shot by police at around 2pm today in #Streatham High Road has been pronounced dead," London's Metropolitan Police said on Twitter.
"The circumstances are being assessed; the incident has been declared as terrorist-related."
The force added: "We believe there are two injured victims. We await updates on their conditions."
Eyewitness Gulled Bulhan, a 19-year-old student, told Britain's domestic Press Association news agency that he saw the dramatic events unfold.
"I saw a man with a machete and silver canisters on his chest being chased by what I assume was an undercover police officer -- as they were in civilian clothing," he said.
"The man was then shot. I think I heard three gun shots but I can't quite remember."
Bulhan added he then sheltered in a library as other passers-by ran into nearby stores.
The force urged people to avoid the area while the emergency services were responding.
London's Ambulance Service said it had "a number of resources" attending the incident on Streatham High Road in the largely residential neighbourhood.
Unverified footage posted to social media purporting to capture some of the incident showed armed police officers surrounding a man lying on the ground on Streatham High Road.
They then abruptly moved away, urging onlookers to move back, as other emergency vehicles arrived at the scene.
Britain has seen a spate of terrorist attacks in recent years.
In the most recent incident on November 29, 2019, convicted terrorist Usman Khan killed two people before being shot dead by police on London Bridge.