Police are looking to speak to the driver of a second vehicle that was close by when a car mounted a pavement and struck pedestrians in north-east London.
Five people were injured in the collision in Stamford Hill on Friday morning.
The Metropolitan Police said the incident is not being treated as terror-related and no arrests have been made.
The driver of the vehicle involved is assisting them with their enquiries.
The force said officers were particularly keen to speak to the driver of a second vehicle – a Toyota Previa – who was in “close proximity” to the collision and may be able to provide further details of the incident.
London Ambulance Service (LAS) said five adults were treated at the scene, with four taken to a major trauma centre and the fifth taken to hospital by a crew from the Hatzola volunteer ambulance service.
Despite initial concerns, none of those involved is in a life-threatening condition and their families have been informed, the Met confirmed.
Graphic CCTV images seen by the PA news agency show the silver Toyota car veering from the bus lane on to the pavement.
The vehicle strikes several pedestrians, including one who is sent hurtling through the air before his body hits a stationary car.
The silver car then crashes into a tree.
One resident said the incident, which happened at around 9.30am, “could have been so much worse” as the road had been full of children walking to school in the preceding half hour.
An eyewitness told PA the driver of the car was in “shock” after the crash and was overheard telling police his brakes had failed.
The witness, who asked not to be named, said: “I heard a bang, that was when the car hit the bus stop.
“The car was on the kerb and I saw two people flying in mid-air.
“After that he hit a Mitsubishi parked over there and his car did a 90-degree rotation.
“Another guy on crutches got hit.
“A few elderly Jewish gentlemen helped him out the car, people in the shop came out to help.
“I called police and they were here in two or three minutes. I saw five people getting treated including the driver. He was an older-looking man in shock.”
The driver was identified as a furloughed worker at a nearby Kosher grocery store called Breuer And Spitzer by an employee, who declined to name the man.
He said he was in his 70s and had been employed there for as long as 40 years, but had not been working because of health fears over his age.
“He was a very careful man, always big with health and safety. A very nice man,” he told PA.
“We’re all in shock, it’s such a surprise.
“I think something must have gone wrong technically with the car or inside him, a health issue maybe.
“He is such nice man, very careful, very safe, everyone knows him.”
Paramedics and police officers were called to the scene shortly before 9.40am.
An LAS spokeswoman said six ambulance crews, hazardous area response teams and a London Air Ambulance team, who travelled by car, were among those who attended.
The Met is asking anyone who witnessed the collision or drivers who have dashcam footage to contact officers from the Serious Collision Investigation Unit witness line on 020 8597 4874.