A horrific multi-vehicle crash marred the IndyCar race in Toronto on Sunday, with seven cars involved in a frightening pile-up during the latter stages of the contest. Colton Herta took the chequered flag to secure his first victory of the campaign but the main talking point was the huge smash which saw one car flipped upside down.

The incident took place following a restart on lap 73 of 85 when Arrow McLaren driver Pato O'Ward spun on his own while running in sixth place. He was left facing the wrong way on the corner exit, with a number of cars smashing into him in a terrifying pile-up.

Most of the drivers involved got away with minimal damage but Santino Ferrucci was sent flying into the air, with his car inverting as it clipped the fencing before landing upside down. The race was promptly red-flagged to allow the debris to be cleared and the barriers to be repaired.

Ferrucci was able to get out of the car unassisted but all of the drivers involved in the smash were checked over by medics as a precaution. The race was eventually allowed to resume, with Herta leading Andretti team-mate Kyle Kirkwood across the finish line to secure a thrilling victory.

O'Ward later argued that IndyCar officials were calling for a 'massive shunt' by failing to bring out the yellow flags immediately after his spin.

"I had rear locking," he said. "It spun and that's pretty much the end of that. I am so surprised IndyCar didn’t call a yellow, like, you're just calling for a massive shunt. They had a solid five seconds to call yellow and tell everybody that was coming.

"But I'm glad everybody else that was in it is fine. Sorry for the team. Obviously, we were having a better race than what we've had all weekend. It's really been miserable."

Ferrucci also criticised the lack of yellow flags, explaining that he did not see O'Ward's stationary car until it was too late to avoid a collision. He was already struggling to steer properly after a trip into the barriers on the opening lap, which forced him to pit for a new nose.

"First off, I'm very, very thankful to the IndyCar medical team," said Ferrucci. "You know, cars are so safe to have a scary accident like that, just to walk away fine.

"I never saw Pato. Actually, at the start of the race, I had the steering wheel bent trying to avoid Pato and just we were left-hand up, right-hand down [for the rest of the race]. So when I came through there, I never saw Pietro [Fittipaldi] clip him and nothing on the spotters.

"There were no yellows, no nothing, so I didn't know to check up and just super unfortunate. I was trying to take care of equipment, trying to have a recovery day and just a bummer."