English Olympic champion Matt Walls was one of three riders taken to hospital after being catapulted over the barriers and into a horrified crowd of spectators in another high-speed crash at the Lee Valley velodrome on Sunday.

Walls had to be treated for injuries in the stands for 40 minutes – as the session was suspended and the arena cleared of fans – after being sent flying in a multi-rider pile-up on the final lap of the 15km scratch race qualifier.

Two other riders, the Isle of Man’s Matt Bostock, who had to be taken out of the arena on a stretcher, and Canadian Derek Gee, who also nearly landed in the crowd, ended in hospital too.

One man in the crowd also needed treatment for cuts to his arm, and was taken out of the arena bloodied and in a wheelchair, while a young girl also received attention.

All three riders were later discharged, Walls miraculously escaping with just a few stitches needed in his forehead.

Richardson had been preparing in the centre of the arena for his sprint quarter-final decider when the drama occurred.

“It’s always hard when a crash like that happens. You never want to see it – and that was a really bad one,” he said.

“And though you obviously hope everyone’s going to be okay, you just have to focus on your own performance and get the job done.

“You’re in such a tight mental space the whole day – putting it simply, you’re in the zone – and something really bad would have to happen to me to get me out of that mindset.”

His race was delayed until the afternoon session because of the crash, leaving him to face only a 10-minute break before his semi-final, yet he still produced a series of brilliant sprints to take gold.

The crash, though, left serious questions over the safety of both riders and spectators at the 2012 Olympic velodrome, as an inquest into the accident began.

England’s five-time Olympic champ Laura Kenny said she wanted to see the sport do more to prevent “dangerous” incidents.

“I think the crashes are getting worse and it’s because the speeds are getting higher, the positions are getting more extreme,” the five-time Olympic champion said.

“At some point the UCI are going to have to put a cap on these positions. Maybe there should be screens because Matt should not have been able to go over the top and into the crowd – that’s pretty damn dangerous.

“Matt was laughing and making jokes with the paramedics, which is brilliant to hear, but if he’d not gone over, he would have done less damage and certainly done less damage to the little girl.”

Spectators were left stunned when Olympic omnium champion Walls suddenly appeared, sent spiralling into the air and landing in the front seating section of the arena along with his bike.

The 24-year-old had been powering up the banking as the race reached speeds of up to 60kph on the final circuit, trying to avoid others who had tumbled lower down. Eight athletes, including Australia’s Josh Duffy, were caught up in the carnage.

It was the second high-speed spill in successive days after another English rider, Joe Truman, suffered a suspected broken collar bone when taken out unwittingly by Australian Matt Glaetzer in Saturday’s keirin second round.