At least 16 people have been injured - some seriously - after two 'boy racers' ploughed into crowds of car enthusiasts watching them race at a souped-up car event locals had warned police would be dangerous.
The horror unfolded shortly before 10pm in Stevenage, Hertfordshire, when a car pulled out of a car park directly into the path of a blue Nissan 350z believed to be doing 50mph.
The Nissan clipped the black car, believed to be a Toyota GT86, and was sent flying across a central reservation in the road that was crowded with onlookers.
Meanwhile the Toyota was sent careering to its left by the impact, smashing into more spectators who were on the pavement and a grassy bank behind it.
Harrowing footage from the scene in Stevenage, Hertfordshire, showed screaming spectators, many of them just teenagers, desperately trying to help badly wounded victims after they were 'sent flying' by the crash.
Witness Ciaran Connor said he estimated one of the cars was going at 50mph when it hit the bystanders. 'I'm just praying no one has been killed,' he said.
The collision happened at 9.45pm last night during a weekly meet-up where drivers show off their 'pimped' vehicles.
Residents nearby have repeatedly slammed the event and called on police to shut it down, with one saying last night's tragedy was an 'accident waiting to happen'.
The blue Nissan on the right hurtles along the A602 in Stevenage, clipping the slower-moving black vehicle on the left and sending them both crashing into spectators at a Thursday night car meet
The badly damaged blue Nissan was pictured being removed from the scene this morning by the emergency services
Pictures taken this morning showed the black car, believed to be a Toyota, had its roof completely ripped off. It was also seen being taken away from the scene this morning
The blue vehicle, believed to be a Nissan 350z, is seen with its chassis and windscreen damaged after the crash
More than a dozen ambulances and police cars gathered at the scene after the collision last night
A crowd of people react in horror after watching the sickening collision at a car meet event in Stevenage last night
A diagram showing how the collision took place on the A602 in Hertfordshire as two cars ploughed into car meet spectators
Around 400 people had turned up to attend a 'take-over' event where enthusiasts show off their modified or 'pimped' cars on an industrial estate.
It was intended to gather funds for a charity called 4Louis which provides equipment and training to hospitals and medics involved in the death of a child.
Mr O'Connor, 33, was in his car driving past when he witnessed the carnage, seeing a group of children 'go flying' as the Nissan rammed into them.
'There was literally no time to react,' he told MailOnline. 'If we were five seconds later we would have been involved in it.
'They were all between the ages of 14 and 17. It was horrible. The car going faster on the other side of the road went into about another five people.
'Some boy got his arm stuck under the car and I saw people actually trying to lift the car up.'
Moments from disaster: The black vehicle turns into the left-hand lane of the A602 just seconds before it is struck by the faster-moving blue vehicle, sending it into spectators
Police presence: A line of officers at the scene last night after a collision which has left at least 12 injured people in hospital
Police investigators worked late into the night in the aftermath of the crash, which put at least 16 people in hospitals
The badly damaged Nissan remained at the scene through the night with forensics officers analysing the crash
The black car, believed to be a Toyota, came to a rest on a grassy bank that had been crowded with spectators. It appeared to have had its roof removed by firefighters.
Lit up: The blue lights of ambulances and police cars dominate the scene in Stevenage in the wake of the horrific crash
Emergency: Police vehicles respond to the crash in an emergency response which also saw an air ambulance arrive
In the aftermath panicked spectators screamed for help as dozens of emergency vehicles – including the air ambulance – raced to the scene on the A602.
At least 14 of those hurt were hospitalised, Hertfordshire Police said last night. The victims were taken to three local hospitals, and a 'major emergency' was declared.
DID YOU WITNESS THE STEVENAGE CRASH?
If you witnessed the crash or if you have previously tried to get the car meets stopped, please contact us via [email protected] or call 020 3615 1697.
Mr O'Connor, a singer from Stevenage, said one mother arrived to find her son injured and burst into tears, and that one person was lying 'motionless', he said.
The singer, from Stevenage, said: 'I've never seen anything like it in all my life. It was carnage. Kids were crying, I felt helpless. I got out of my car but what could I do.'
Other witnesses too to Twitter to describe the horror they had seen.
'I've just witnessed that horrendous crash in Stevenage, no more than 50ft away from me. I'm still trying to process it all,' one said.
Another added: 'My thoughts and prayers are with all those poor kids who were struck by a car tonight in Stevenage at the car meet.
'Literally never seen a scene like it. Kids lying in the road everywhere missed it by about 10 seconds as was just turning round the roundabout.'
And a third told how they narrowly avoided being among the casualties. 'I was also there and spent over an hour holding one of the girls while the paramedics turned up,' they said.
'I was sat on the grass bank and then moved across the road and sat on the other side approximately five minutes before it happened.
'It may have been a decision that save me and my son. I hope the two injured girls I was with recover along with all the other injured parties.'
Photos from the scene tonight showed the Toyota on the grassy bank that had earlier been crowded with spectators. It appeared to have had its roof removed by firefighters, however it was unclear whether its driver was among the 14 people in hospital.
A police vehicle on the scene after the Thursday night collision in which at least 16 people have been injured
This footage of the car meet in Stevenage, which was described as a charity event, shows spectators on either side of the road before the collision
One report on social media said that at least 10 people had been hit with a large number of emergency services on the scene
Videos posted online, many too harrowing to publish in full, showed dozens of spectators lining both sides of the two-lane road, which runs behind League Two side Stevenage FC's Broadhall Way ground and has a 40mph speed limit. They also crowded onto the low central reservation and grassy banks on either side to watch the cars drive past.
One film showed cars building up terrifying speeds in the moments before the crash.
Afterwards, the Nissan was pictured with a smashed windscreen and screams could be heard in the background as shocked spectators milled around at the scene.
The 'meet' – part of a series organised by the Cruise Herts group that occur on Thursday evenings in Stevenage - was described on Facebook as an 'extra special' one to raise money for families affected by stillbirth and miscarriage.
Locals said they had often complained about the gatherings, but police had failed to shut them down.
'It was an accident waiting to happen,' one resident said.
Three ambulances and two police cars at the scene in Hertfordshire on Thursday night following the horrific crash
The car meet was described on Facebook as an 'extra special meet' to raise money for families affected by stillbirth and miscarriage
Scene of carnage: The two-lane A602 Monkswood Way in Stevenage where the crash happened. One car pulled out of the Wickes and KFC car park from the side road shown on the left, and was hit by a car speeding down this left-hand lane
Event organiser Rix Sidhu, 29, who leads the Cruise Herts car club, told MailOnline the group are not boy racers but 'car enthusiasts' and that the event was ruined by a minority of the estimated 400 total attendees.
He told MailOnline: 'We don't condone street racing, we organise static meet-ups. We park up and walk about and admire the cars, we've even had families come in the past. We've been doing this for 10 years.
'But we can't control everyone and we don't promote this. We are not boy racers, we are car enthusiasts.'
He said last night's event was meant to raise money for families affected by stillbirth and miscarriage but after the horrific scenes he would 'never hold the event again'.
'Our thoughts go out to the victims involved and thank you to those who helped,' he said.
The injured bystanders were taken to the Lister Hospital in Stevenage, Watford General Hospital and to the Princess Alexandra Hospital in Harlow, Essex.
A Hertfordshire Police spokesman said last night: 'Police and other emergency service colleagues are currently at the scene of a serious road traffic collision on Monkswood Way, Stevenage.
'Two cars were involved in the collision which occurred at around 9.45pm. There were a number of people in the area at the time and 14 people are being are presently being treated for injuries, some of which are serious.
'Officers from the Beds, Cambs and Herts road policing unit are investigating and emergency services are expected to remain at the scene for some time.'
Did you see what happened? Get in touch - [email protected] or call 020 3615 1697.