The incident happened in Kingston Road near Hartfield Road just before 3.35pm yesterday (August 26).
Officers and London Ambulance Service crews attended and found four people injured.
They were treated at the scene before being taken to hospital where their conditions are unknown.
Kingston Road was closed both ways between Hartfield Road and Dorset Road as the incident was dealt with.
All closures have since been lifted.
We have contacted British Transport Police for further information.
A spokesperson for London Ambulance Service said: “We were called at 3.36pm today (26 August) to reports of a road traffic collision on Kingston Road, Wimbledon.
“We sent ambulance crews, incident response officers and paramedics from our hazardous area response team.
“The first paramedic arrived in around five minutes.
“We treated four patients at the scene.
“We took one of them to a major trauma centre and took three patients to local hospitals.”
