At least 14 people have been hurt after two 'boy racers' ploughed into crowds of youngsters at a car meet in Stevenage.
Footage of the crash shared on social media showed the vehicles slamming into bystanders at the charity event on the A602 in Hertfordshire.
Witnesses said they saw 'kids lying everywhere' as rescue services rushed to the scene.
Pictures of the aftermath showed a huge emergency response, with police confirming that 14 people were injured, some seriously, and 12 people were taken to hospital.
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.
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He told Mirror Online: "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.
"The first car hit three or four people. I think the slow car went into eight to nine people but it was going slow.
"There were about 200 people there. The majority of them were 15, 16 or 17."
Mr O'Connor said he saw a car travelling at speed hit a group of youngsters.
He added: "They went flying. A car pulled out of a retail park and this other car... basically dodged it and took these kids out."
The crash took place at around 9.45pm during a weekly meet of the modified car club Cruise Herts.
It is not yet clear whether members of the club were involved in the smash.
One witness said: "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."
Another witness added: "I was also there and spent over an hour holding one of the girls while the paramedics turned up.
"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."
The collision took place near a Wickes DIY store on the A602 as one car pulled out of Roaring Meg South car park onto the road.
At least 30 members of the emergency services are at the scene, according to witnesses.
In the distressing footage shared on social media, a car can be seen hurtling past another vehicle before mounting the curb and hitting spectators.
It sent the slower-moving car ploughing into another group of people on the other side of the road.
A major incident has been declared at Lister Hospital in Stevenage as emergency services deal with the casualties.
A helicopter is reported to have arrived at the scene as casualties are taken to hospital.
The car meet was described on Facebook as an 'extra special meet' to raise money for families affected by stillbirth and miscarriage.
On the Cruise-Herts Facebook page, a post read: "This Thursday night meet is an extra special meet we as a group are raising money for the excellent charity of 4Louis who help supporting families through the heartache of miscarriage stillbirth and child loss.
"This is a Strictly Static Meet & Any Antisocial Behaviour Will Not be Tolerated! Any Such Behaviour will be Dealt with by the Local Authorities!! So strictly NO Wheel Spins NO Burnouts and NO Drifting."
A Hertfordshire Police spokesman said: "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."
Police are looking to speak to anyone with footage of the incident.
A spokesman for the East of England Ambulance Service said: "Twelve people have been taken to three hospitals including the Lister Hospital in Stevenage."
