McLaughlin had spun through the grass exiting the pit lane as he pushed on his new, alternate-compound Firestone tyres, briefly entering the track at the apex, which caused Power to run up the track to avoid him through Turn 2.
The two-time IndyCar champion hit the wall and spun back across the track and into the path of Chip Ganassi Racing’s Marcus Ericsson, who piled into Power and wrecked both cars.
It is the first time that IndyCar has used the softer tyres on an oval, and the practice session topped by Penske's Josef Newgarden was the only opportunity for teams to evaluate the rubber before the race as their use is banned in qualifying.
McLaughlin held his hands up to causing the accident, but not before Power had branded him a “dumbarse” on TV.
“It was my own fault,” McLaughlin told NBC Peacock. “Massive apologies to Marcus and the #8 crew and the #12 crew of Will.
“I was pushing the out lap on my brand-new set of red tyres and I cut the inside just a little bit coming off the apron and it must still be a little bit wet or something [after earlier rain delayed the session].
“It was very scary. I heard my spotter saying ‘car coming into [Turn] 1’ so I just tried to lock it down as best I could.
“I hate to see what happened, especially to a team-mate but not only that to competitors, and it was a really dangerous situation, but you try and look for every little bit on in- and out-laps and I didn’t see that it was damp, maybe because it was a little bit dark, and that’s no excuse but I was just trying to find that little bit.
“Two others paid for it and I feel terrible to be honest.”
Power, who suffered a similar wreck in practice at Road America in a clash with Ericsson’s team-mate Scott Dixon, was apoplectic in the aftermath.
“I saw some dumbarse down on the apron spinning and, unfortunately, I had to go up and got in the wall,” said Power. “Just destroyed my car, got hit, and I’m just really pissed.
“Got no option but to rebuild and do my best, I’m just pissed off getting screwed by other people’s screw ups. Same at Road America with Dixon.”
Ericsson will require a new chassis being built up overnight as the damage to his car was deemed irreparable on site.
“I saw McLaughlin on the inside there, spinning, and I saw Will going high,” said Ericsson, whose move to Andretti Autosports next year was announced earlier this week.
“I was trying to figure out where to go, but obviously I had the steering lock and all the load in the car when you go through there.
“I saw he was going up against the wall, so I tried to go low, but then he just came spinning down. It’s really a shame, I feel bad for the #8 crew they’ve done a really good job all weekend with the race car.
“We were feeling really good all practice and it ends like this… very frustrating.”
