Scarborough Gold Cup was cancelled at 3pm after two separate motorbike crashes left six people injured, including two seriously at the track.
Jamie Coward, from Hebden Bridge, tweeted his apologies after crashing through the fence at Drury’s Hairpin during morning qualifying.
Three people were taken to hospital, including one who was seriously injured.
He said he was "very upset and shaken by what had happened", adding: "Really sorry to spectators involved in my accident today there was nothing I could have done."
His apologies have won support, with people responding positively to the tweet.
One posted: "Says a lot about you big man to get on and tweet that best wishes for all involved."
Racing was abandoned after a second rider crashed at the same corner three hours later, hurting himself and two others.
In a statement, the circuit said: "Today we have had two serious incidents involving a number of spectators.
"Our medical personnel, together with the marshals and officials of the club, local police, NHS, ambulance staff and helimeds have treated all the injured.
"In view of the seriousness of these incidents and our requirements to call on outside assistance to help with this treatment, we have reluctantly taken the advice of everyone concerned and have decided to cancel the rest of the meeting.
"We sincerely apologise to you all for taking this decision and hope you will understand our difficulties in this unprecedented situation.
"We wish you all a safe journey home."