A man aged in his 40s was taken to hospital with head injuries after a fight in Thornton Heath.
It broke out in Brook Road at the junction with Quadrant Road at around 2.50pm on Monday.
A man riding an e-scooter aged in his 20s was detained a short time later in Green Lane.
He was arrested and taken into custody.
Police and ambulance crews attended the scene.
The condition of the man taken to hospital was later confirmed as not life-threatening.
Any witnesses who are yet to speak with police are asked to call 101, quoting reference 4263/29aug.
A Metropolitan Police spokesperson said: "Police were called at around 14:50hrs on Monday, 29 August, to a report of a fight in Brook Road at the junction with Quadrant Road in Thornton Heath.
"Officers attended the location along with London Ambulance Service.
"A man, aged in his 40s, was taken to hospital suffering head injuries.
"His condition was later confirmed as not life-threatening.
"A man riding an e-scooter was detained a short time later in Green Lane.
"The man, aged in his 20s, was arrested and taken into custody.
"Detectives from the Met’s South Area CID are investigating.
"Any witnesses who are yet to speak with police are asked to call 101, ref 4263/29aug."
A London Ambulance Service spokesperson said: “We were called at 2.53pm on Monday 29 August to reports of an assault on Brook Road, Thornton Heath.
“We sent an ambulance crew, a medic in a fast response car and a clinical team manager to the scene.
“We treated a man at the scene and took them to hospital.”
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