The five people on the motorbikes were thrown in the air and fell hard on the highway. All happened in five seconds, before they were rushed to hospital with injuries.
Debris from the bikes, helmets, shoes and slippers were scattered over the road.
An eyewitness said the car was driving at a high speed when it crashed into the motorbikes. When it was around 20 m from the red light, it did not slow down but did manage to avoid a stopping truck before hitting the motorbikes that were close to the roadside.
The driver, Nguyen Chi Hao, tested negative for drugs and alcohol, though he has not reached the age to drive a car yet.
Initial investigation found the accident happened as Hao did not pay attention to the road when driving.
Police are investigating further.