Three people, including two children, were left with serious injuries following a collision with a vehicle in Ruislip.
It took place in Field End Road on Monday, December 13. Officers attending discovered a woman in her 30s and two boys injured.
While the woman and one of the boys were taken to hospital following the attendance of paramedics, but upon assessment were not found to be life-threatening.
As well as police, two ambulances and a medic in a car attended, with an air ambulance sent as well.
According to a Metropolitan Police spokesperson, the driver of the vehicle was arrested at the scene on suspicion of driving officers. He was taken into custody but has since been released under investigation pending further enquiries.
There are no police appeals at this current time.