While the latter pair walked away from the incident, Crowley and Tylicki were taken to hospital in Tooting with suspected spinal injuries, and the meeting was abandoned.

The Injured Jockeys Fund later announced Crowley had been allowed home, and that Tylicki remained in intensive care but was conscious.

A statement said: "Following the incident at Kempton Park racecourse this afternoon, jockey Jim Crowley has been discharged from St George's Hospital, Tooting, to return home with his family.

"Freddy Tylicki, also involved in the incident, is in intensive care in a stable condition.

"He is conscious and there will be a further update tomorrow once more is known."

The accident occurred as the field rounded the home turn in the one-mile heat, the third race on the card.

Nellie Deen was tracking the pacesetting Madame Butterfly in the hands of Tylicki when the pair suffered a heavy fall.

Crowley and Electrify were racing immediately behind and were brought down, as was Drowne's mount Skara Mae.

Durcan was also caught up in the melee and was unseated from Sovrano Dolce.

Tylicki and Crowley were attended to on the track for some time before being taken to the major trauma unit in Tooting, with Tylicki travelling by air ambulance.

With racing having already been delayed for over an hour, the decision was made to abandon the remaining four races.

Kempton clerk of the course Barney Clifford told Racing UK: "We gave racing every chance. Having discussed it with jockeys and the stewards, the unanimous decision as a mark of respect for the two lads that have been injured, Jim and Freddy, was that we abandoned racing.

"I touched base with Steve Drowne on the way down to the incident and he was fine.

"Ted was quite shook (up) and a little bit lame.

"I believe the doctors did touch base with both of them and I believe they were okay.

"The reality is, Flat or National Hunt racing, it's a dangerous sport.

"You don't expect those things to happen on the Flat. I just hope and pray that Freddy and Jim are okay."

Crowley has enjoyed a career-defining year in 2016 with the 38-year-old being crowned champion jockey at Ascot only last month.

A one-time jump jockey, Crowley was a 66-1 outsider for the riders' title at the start of the year but enjoyed a stellar second half of the campaign including 46 winners in September, a figure which surpassed the previous record of 45 wins shared by legendary names of the Turf, Fred Archer and Sir Gordon Richards.

Crowley was duly named the leading rider of the campaign at Ascot on Champions Day.

While Tylicki was not hitting quite those heights, 2016 provided two red-letter days for him as he notched his maiden Group One win on Speedy Boarding at Deauville in August before following up on that filly in the Prix de l'Opera on Arc weekend at Chantilly.

The 30-year-old was also named champion apprentice back in 2009 and counts the John Smith's Cup among his other previous big-race victories.

Frankie Dettori, riding in Australia in the early hours of Tuesday, was among those to send his thoughts to Crowley and Tylicki via social media.

He tweeted: "Sending my best wishes and speedy recovery to Freddy and Jim."

Leading jumps trainer Nicky Henderson added: "Thoughts very much with Jim Crowley and Freddy Tylicki after Kempton falls. This further highlights the risks jockeys take every day."