A high-speed car crash in Stevenage has left 17 injured after two vehicles collided at up to 70mph, eyewitnesses said.
Hertfordshire Constabulary said two cars were involved in the collision and urged any witnesses to get in touch, especially those with footage of the incident.
Video posted to social media showed the cars colliding and rebounding into crowds lining the side of the road.
Taking to Twitter shortly afterwards, one eyewitness calling themselves @WhoToBeAFC, said the incident was "horrific".
Calling the drivers "boy racers", they said that a car ploughed into people who were watching on.
The East of England Ambulance Service said it had taken 12 people to three hospitals - Lister Hospital in Stevenage, Watford General Hospital and The Princess Alexandra Hospital in Harlow.
An air ambulance also attended the incident.
The crowd had gathered for a weekly meet of modified car club "Cruise Herts", which was raising money for charity. It is unknown whether the drivers involved in the crash were associated with the group.