Pictures from the scene of a fatal motorbike crash in London show a major emergency services presence.
A teenager, who was riding the bike with a pillion passenger, allegedly ran a red light in Oxford Street at 6.45am on September 25.
The motorcycle, which failed to stop for police, was then followed into Tottenham Court Road.
A short time later, it was involved in a crash with a taxi and street furniture near Warren Street tube station.
The 18-year-old was given treatment by paramedics but was pronounced dead at the scene.
The passenger, who was reportedly found to have a machete, was taken to hospital for leg and arm injuries.
He was later arrested.
Watchdog the Independent Office for Police Conduct (IOPC) has launched an investigation, and an internal investigation has been launched by the Met’s standards department.
Pictures from the scene show a major police presence as the incident is dealt with.
Shocked onlookers can be seen in Tottenham Court Road as police respond.
A blue and white forensic tent has also been erected at the scene.
A spokesperson for Metropolitan Police said: “A man has died in a collision with a taxi and street furniture while the motorcycle he was riding was being followed by police officers.
“A pillion passenger on the motorcycle sustained non life-threatening injuries and was arrested after being found with a machete.
“At around 6.45am on Monday, 25 September, two officers on patrol on marked police motorcycles became aware of a motorcycle travelling through a red light on Oxford Street.
“The motorcycle, which failed to stop for police, was being ridden by two males. It was followed into Tottenham Court Road.
“A short time later, the motorcycle was in collision with a taxi and street furniture on Tottenham Court Road near to Warren Street tube station.
“Officers provided first aid prior to the arrival of ambulance colleagues.
"Despite their efforts, the rider of the motorcycle was pronounced dead at the scene.
"The man's family will be supported by specialist officers.
“The pillion passenger was found to be in possession of a machete. He has been arrested and taken to hospital for treatment to leg and arm injuries.
“The Met’s Directorate of Professional Standards (DPS) launched an investigation alongside colleagues from the Met’s Roads and Transport Policing Command.
“The Independent Office for Police Conduct have been informed and we are advised that they have launched an independent investigation.”
The full statement from the IOPC says: "We can confirm we have begun an independent investigation into the circumstances of a fatal road collision involving a motorcycle in central London this morning (Monday).
“We understand the collision took place at around 6.45am after the motorcycle had failed to stop for two marked Metropolitan Police Service (MPS) motorbikes in Tottenham Court Road.
“Shortly afterwards, the driver of the motorcycle, aged 18, is understood to have been in collision with a taxi and sadly died at the scene.
"A pillion passenger, aged 17, sustained non-life threatening injuries.
“After being notified by the MPS, we have sent investigators to the scene and to the police post-incident procedure to begin our enquiries.
“Our thoughts are with all those affected by this tragic incident.”