His vehicle shot across the track, through the grass and hit an interior wall, then back across the track for a third hit of the wall.
The wreck comes a day after Alonso passed the race's refresher test but left the track disappointed after being unable to get any additional practice time in because of an electrical issue with his vehicle. The team changed the alternator and electrical loom and he was back on track Wednesday. Brown is expanding McLaren and has an eye on a full-time IndyCar entry as early as next season.
Alonso's auto was damaged enough that despite their initial strategy, McLaren has elected to bring in their backup vehicle that was prepared by Carlin. Qualifying for the 33 spots in the field begins Saturday; Alonso, one of 36 entrants, has been near the bottom of the speed charts.
Alonso's crash was the attention-grabbing moment on the second day of prep for the May 26 race. The 37-year-old was then helped out of his wrecked auto but looked unhurt. Chip Ganassi Racing said it would go to a backup vehicle for Rosenqvist.
Josef Newgarden continued Team Penske's strong build-up by setting a 228.856mph in his Shell-liveried auto, but it wasn't a flawless day. That was better than Scott Dixon's 228.835 miles per hour in the No. 9 PNC Bank Honda.
There were a total of 3,219 laps completed today with Jordan King of Rahal Letterman Lanigan Racing adding the most laps to the day's tally with 132.
Alonso, the retired Formula One champion, is making his second appearance in the Indy 500 in his quest to win motorsports' version of the Triple Crown. He also competed in the 2017 race, but after a promising day as the race rookie led two dozen laps, he suffered engine failure and finished 24th. He led laps and was a contender until his engine failed, bringing a halt to a almost flawless month for the Spaniard at Indianapolis.
Things aren't looking good for Spanish racer Fernando Alonso as he prepares for his second attempt at the Indianapolis 500.
He said the Indy wreck was not at all similar.
"I was behind Colton (Herta) and just trying to run the vehicle in traffic, and I just felt a very sudden change of having a bit of push, and it went very loose, very fast", Rosenqvist said.
It will be Clarkson's second consecutive performance of the national anthem at the Indianapolis 500 and the third overall. I think we need to be a bit better in traffic.