The incident happened in Mill Hill Broadway at the junction with Flower Lane shortly after 7am today (September 1).
Police said that the driver of the car was treated for shock at the roadside.
London Ambulance Service said that two people assessed by paramedics and taken to hospital.
No injuries were reported among bus passengers.
Police confirmed that no arrests have been made, but both drivers are assisting with enquiries as investigations continue.
The Broadway was closed in both directions for several hours, causing disruption to morning traffic and affecting bus routes 221, 240, 303 and 688, which were placed on diversion.
Recovery teams worked through the morning to clear the vehicles from the road, and the route was reopened at around 1.15pm.
Officers are appealing for anyone who witnessed the crash to call 101 and quote reference 1067/1SEP.
