Michael Cole of Dale Coyne Racing, Wilson's team, and Daniel Martin of Dragon Racing, Bourdais's, were treated and released from the infield care centre.
Chuck Homan and Raffi Aroyan, both of Dragon Racing, were taken to St. Michael's Hospital for evaluation of lower leg and foot injuries and subsequently released.
Both Bourdais and Wilson returned to the track after the accident and, in fact, Wilson later spun into a tire wall when he tangled with a car driven by Alex Tagliani of Montreal. No one was hurt in that incident.
Said Wilson later: “I came down pit lane and the car refused to go into neutral. I was stuck in first (gear). On top of that, these carbon brakes don't work when they're cold, so I was hard on the brakes and I couldn't stop.
"At the last second, I tried to drive into the wall to take speed off but those guys were there and had no idea I was coming.”
The turnout for Free Friday was steady but not overwhelming (admission was waived for the day, which was sponsored by the Honda Dealers of Ontario in return for a donation to Make-A-Wish Canada). It was very warm at Exhibition Place and many of the spectators spent most of their time inside the air-conditioned Direct Energy Centre.
The support race Star Mazda Series will kick off Saturday's on-track activities at 8 a.m. The Indy cars will go out for final pre-qualifying practice at 9:45 a.m. with qualifying commencing at 1:05 p.m.
In addition to Hinchcliffe, Tagliani and de Silvestro will be assessed 10 grid-position penalties post-qualifying for unauthorized engine changes.
The featured race of the day Saturday will be the Firestone Indy Lights, with the green flag scheduled to be waved at 4 p.m.