"I'm pretty sure I know which one it was," said race winner Jeff Gordon. “We were walking down pit road, the umbrellas weren't doing any good, there was a huge, huge crack from lightning. You could tell it was very close."
He was clearly shaken by news of the casualties. "I mean, that's the thing that's going to take away from the victory, is the fact that somebody was affected by that."
"I just got home and found out about the tragic loss we had today at Pocono," wrote fellow driver Mark Martin on Twitter. "I am so sorry for the family's [sic] that we're involved."
"I want to throw up after reading the days of today's tragic death," Brad Keselowski added on the social media site. "How terribly, terribly sad ... My condolences to the family.
There will inevitably be questions over whether the Raceway and NASCAR should have done more to ensure the safety of the spectators, given that the incoming storm had been tracked for such a long time before it arrived.
An official severe storm warning was issued at 4.12pm local time, but NASCAR allowed the race to continue to run for another half hour before throwing the red flag at 4.42pm for rain as the storm arrived over Pocono.
A spokesman for the track said that public address announcements had been made as soon as the race was stopped warning spectators to take cover, and that alerts had also been sent out via the Raceway's Twitter feed.
NASCAR spokesman Kerry Tharp disagreed with suggestions that they should have acted even quicker to stop the race and order the evacuation of the grandstands: “If there was a situation that warranted us to halt a race to threatening weather, we would certainly do that," he said.