In the final lap of the men's 15km scratch race, England cyclist Matt Walls crashed into the crowd, leaving one spectator "covered in blood."
The race was abandoned and medical teams had to race onto the track as a second cyclist, Matt Bostock from the Isle of Man, was taken out on a stretcher.
One fan had to be taken out in a wheelchair and was left "covered in blood" after Matt Walls landed in the crowd.
All racing stopped and spectators were cleared from the Lee Valley VeloPark in London.
The Olympic champion rider was attempting to avoid riders who had been involved in a crash lower down the banking but as he rode up, he hit another wheel and was sent over the top.
A Team England spokesperson said: "Matt is alert and talking (as he has been throughout) and is being given medical attention in hospital."
In total eight riders went down in the crash on the last lap of the race, and coaches and medics immediately rushed to help.
Mathias Guillemette, rider for Canada, was disqualified from the race for causing the crash.