Five people were seriously injured when two cars crashed at high speed and hit spectators at a memorial car meet in Lincoln on Saturday night.
It happened just after 10pm on Whisby Road when people were gathered for the memorial of a popular biker who died in a crash earlier this month.
Police said the vehicles collided at high speed, crashed into spectators, and then left the road and ended up in a ditch.
Five people were taken to hospital. Four people are in a serious condition and another considered critical, who had to be put in an induced coma.
Detective Superintendent Peter Grayson said: “This is a very serious collision with profound physical consequences for those injured.
“The event had a large crowd, and we would like to speak to anyone who has not yet been spoken to as part of our investigations.
“We would also like to hear from anyone who was in the area that evening, and witnessed the incident, the gathering, or has dashcam or mobile phone footage of the incident itself.
“We have been on scene since just after 10.15pm last night, and will remain in the area during today as we carry out our initial enquiries.”
The stretch of road was closed until around 8.30am this morning.
If you have were at the incident and have video footage which can help with this incident, there are a number of ways to get in touch: