Local people and witnesses to a crash at a car meet in Stevenage that left 17 people injured have said the event was not organised or policed properly.

For 17 years, drivers of modified cars have gathered in the Hertfordshire town to parade their vehicles for fellow enthusiasts. Thursday’s event, which was raising money for a charity supporting bereaved parents, turned to disaster when some of the spectators watching from the side of the road were hit following the crash between a Nissan 350Z and a Toyota GT86.

One of the vehicles was estimated to have been travelling at 60-70mph when it hit spectators on the single-carriageway section of an A-road. Police said two of the injured were in a serious but not critical condition in hospital.

Rix Sidhu, 29, from Cruise Herts, who organised the car event, said he did not recognise the two drivers involved and they were not members of the group.

He said police were aware of their regular gatherings but no officers attended Thursday’s event.

Sidhu said he was “devastated” over the incident, adding: “The problem is we can’t control the people driving. Last night, people were recklessly driving up the dual carriageway.

“There were bodies lying on the road, people bleeding. There were 15 of us lifting the car up to get a person out.

“We are car enthusiasts, not boy racers. Families come down to the events with young children. We want people to show off their pride and enjoy. If you want to race, spend money on going to a track event.”

Hundreds of spectators had gathered for the showcase. Local people say the regular gatherings had taken place in other parts of the town previously and Stevenage is a popular location for car aficionados due to its numerous long straight roads from the Roman period which have been converted into dual carriageways.

Lorna Strutt drove past the scene of the crash 15 minutes after it happened. “It was a charity event, perhaps that’s why there were more standing around,” she said. “Everyone has to have their bit of fun. If it is contained in a car park as usual then it’s fine. But last night was bloody dangerous.

“The road wasn’t organised to be shut off. Usually there is police presence.”

Dark tyre marks shaped in figure eights remained in the car park of the retail park where the event was held.

One car enthusiast, from nearby Royston, said: “You get a lot of people not part of the group then you get hassle, they are outsiders.

“It’s a show and meet but they watch the old films and think let’s go racing.

“When I used to do it, there was a lot of racing and noise when The Fast and Furious films came out.

“I don’t know why local councils and police don’t work with the groups. Out in America and Australia they close roads and do diversions, police work with them.”

Another man showed the Guardian a video circulating on WhatsApp from a witness, of teenage boys being hit by one of the vehicles.

He said: “It is a nuisance but there is nowhere for them to do it. They come to an industrial estate because it is closed at night. It is dangerous.”

Local resident Mike Johnson said: “Spectators are just as much to blame. They stand too close knowing they could spin out of control. It should be organised properly with people standing well back.”

Melainne Cole said they should have “barriers in the right place and right time or go to a race track”.

One woman, who works in a furniture store nearby, said: “Police don’t come out. My boss rings them every time, she has been complaining to them for a couple of months.

“You see the spinning wheels in our car park, it is always a hassle. I knew it was going to happen eventually, police let it go for so long.”

Hertfordshire police said they were investigating the incident and no one had been arrested.

Ch Insp Alicia Shaw said: “We weren’t aware of this event taking place and we weren’t aware of such large numbers attending the Stevenage area.”

Shaw said officers had attended events in the past and handed out warnings or seized cars when they were being driven dangerously.

Hertfordshire fire and rescue service said crews had cut one person trapped in a vehicle free and provided “trauma care” to a number of injured people.