London Ambulance Service has issued a statement as a girl is in a critical condition after being hit by a bus in Bexleyheath.
Police and paramedics were called to the incident on Watling Street just after 9am on August 3.
They sent several emergency units, including ambulances, paramedics in fast cars, an incident response officer, and London's Air Ambulance.
The first crew arrived in one minute.
They treated two children at the scene and then took them to a major trauma centre in London.
The nine-year-old girl is in a critical condition and her five-year-old brother, who was also struck, was taken to hospital as a precaution.
A spokesperson for Metropolitan Police confirmed that the driver was arrested on suspicion of causing serious injury through dangerous driving and drug-driving.
He was taken into police custody where he remains.
The siblings were with a family member when the crash occurred on Saturday morning, the force added.
Detectives have appealed for any witnesses to come forward and to call 101 quoting reference 2309/03Aug.
A London Ambulance Service spokesperson said: “We were called at 8.59am on Saturday 3 August to reports of road traffic collision in London Road, Dartford.
“We sent a number of resources the scene, including ambulance crews, paramedics in fast response cars, an incident response officer and London’s Air Ambulance.
“The first of our crews arrived in one minute.
“Our crews treated two children at the scene, before taking them to a London major trauma centre by road.”
The full Metropolitan Police statement says: “At 09.05hrs on Saturday, 3 August, police were called to a bus in collision with two children on Watling Street near the junction with Halcot Avenue, Bexleyheath.
“A nine year-old girl was taken to hospital by ambulance. Her injuries are being treated as life-threatening.
“A five year-old boy was taken to hospital as a precaution.
“The children are siblings who were with a family member at the time of the collision.
“Officers are providing support to their family.
“The male driver of the bus was arrested on suspicion of causing serious injury through dangerous driving and drug-driving.
“He remains in police custody.
“Any witnesses to the collision who are yet to speak with police are asked to call 101 quoting reference 2309/03Aug.”
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