The drivers of both cars involved in a crash last night which injured 18 people have been interviewed as part of the police investigation.
Emergency services were called to Monkswood Way in the town following the collision, which occurred at around 9.45pm between the junctions for London Road and Broadhall Way.
In total, 18 people have been treated for injuries - two described as serious - after the two cars crashed before hitting a number of pedestrians.
Video footage shows a car coming from the direction of London Road colliding with a car coming out of the Roaring Meg South car park - where a weekly meet of members of modified car club Cruise-Herts was taking place.
Assistant Chief Constable Nathan Briant said: "Hertfordshire Constabulary is continuing to work with partners to fully understand the events of yesterday evening in Stevenage.
"To date we have identified the drivers of both cars involved in the collision and they have been interviewed as part of the on-going investigation.
"Hertfordshire Constabulary has never received prior warning of events such as the one yesterday evening, however, we have previously responded to such gatherings where concerns have been raised by the public.
"Whilst the events do occur regularly the meeting yesterday evening appeared far larger in nature than previous events, and it is now understood that an organiser had publicised the meeting on social media as a charity event. "
Police are also asking anyone who has information to contact them.
Assistant Ch Con Briant said: "Last night we identified more than 130 witnesses and an investigative team has been formed to ensure each of these is contacted to obtain their statements. We are also aware of a large number of people leaving the area prior to our arrival, among these are likely also to be further witnesses to the collision.
"We would urge anyone who was at the scene to make contact with us as soon as possible. In particular we would ask that anyone with video or dashcam footage of the incident itself, and of the gathering before the incident took place, to make contact via optephra@herts.pnn.police.uk or by calling 101."
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