Watchdogs are investigating after a man was Tasered "a number of times" and then shot by police.
The man was taken to hospital following the shooting near Kilburn Lane, Brent, north-west London.
Officers initially went to an address in Claremont Road at around 2.45am, and a short time later the man was shot in Oliphant Street.
The Independent Police Complaints Commission (IPCC) is investigating the shooting.
The IPCC said on its website: "There is evidence at this early stage to indicate a single shot was fired by a police officer. There is also evidence that Taser was used a number of times during the incident.
"The IPCC will examine all of the circumstances surrounding the shooting, including the use of Taser.
"Investigators are downloading information from Tasers to establish how many discharges were made and police officers have been providing their initial accounts of the incident. CCTV retrieval and house-to-house enquiries will take place."
Two knives were found at the scene, which will also form part of the investigation.
IPCC Commissioner Cindy Butts said: "It's essential when the police use potentially lethal force that there is a thorough and independent examination of that decision. I would like to assure all those concerned that we will investigate all of the circumstances surrounding this incident."
A Scotland Yard spokesman said earlier: "Officers discharged Taser but with no apparent effect on the man.
"Firearms officers attended in support of local officers and Taser was discharged, again with no apparent effect. The man was then shot by police."
Nobody else was injured during the incident and the Metropolitan Police's Directorate of Professional Standards has been informed.
The man's condition is described as stable, the IPCC said.