The footage taken by spectators in the moments leading up to the crash, shows cars speeding up and down the streets at an event in Stevenage designed to raise money for bereaved families.
Crowds are lined up along the pavements watching the cars when a black Nissan 350Z turns into the street and is hit by a blue Toyota GT86.
Spectators can be seen reacting to the horror crash before it happens.
The cars then plough into the crowds, injuring more than 17 people, with some believed to have life-changing injuries.
Witnesses described 'kids lying everywhere' after the vehicles ploughed into the crowds watching the cars.
Ciaran O'Connor, 33, who witnessed the crash while driving home from an open mic night, said he saw three or four youngsters lying motionless in the road.
He said: "You could just see kids on the floor not moving. I saw at least 10 people injured. One boy had quite a bad arm injury.
"Another boy had his arm cut open and his mum was really upset. She came 15 minutes after the incident and grabbed him and hugged him.
Pictures of the aftermath showed a huge emergency response, with police confirming that 17 people were injured, some seriously, and 12 people were taken to hospital.
Witnesses described the blue car as being driven at around 70mph when the accident took place.
Organiser Mr Sidhu told PA a small number of cars "went rogue" and left the car park, where crowds lined the main road to capture footage of the vehicles at speed.
Mr Sidhu said: "We are devastated.
"I've been running this for 10 years and we have never had one incident."
