Team England said in an update: “Matt is alert and talking — as he has been throughout — and is being given medical attention in hospital.”
Witnesses said that, because of the gradient of the banking, spectators in the front row had been unsighted for the crash.
One man received treatment for cuts to his arm while a young girl also received medical attention.
Walls had been trying to avoid riders who had fallen. The stricken pair of New Zealand’s George Jackson and Australia’s Josh Duffy slid up the banking, forcing Walls up on to the barrier and then over it.
Canadian Derek Gee also surfed the top of the barrier but managed to avoid following Walls into the stands.
The Isle of Man’s Matt Bostock was also taken to hospital with head and shoulder injuries while Canadian Mathias Guillemette was disqualified for causing the initial crash.