Incredible footage of the crash, posted on Twitter, shows the moment Jay Howard's car bounced off a wall, skid and crashed into Scott Dixon's vehicle, sending it airborne. Mr Dixon's vehicle then briefly slid along the safety fencing on the inside of the track. Debris from his car went flying across the race track and flames briefly shot out from its back end.
Oh my god it's incredible that Scott Dixon is OK. pic.twitter.com/2nA1DRIIRo— Nick Bromberg (@NickBromberg) May 28, 2017
Both drivers were checked and cleared by medical professionals after the crash.
Mr Dixon, of New Zealand, won the Indy 500 in 2008. This clip shows the crash as it happened from his point of view.
Mr Dixon took to Twitter to reassure fans of his well-being, tweeting it was a "wild ride."
I'm elated to hear @scottdixon9 is ok. That was nasty. Everyone was pushing hard from lap 1 today, glad all are safe.— Graham Rahal (@GrahamRahal) May 28, 2017