Stefan Wilson sustained a fractured vertebrae in a two-car crash during practice on Monday ahead of the Indianapolis 500.
Wilson was taken to an Indianapolis hospital via ambulance, where tests discovered a fracture to his 12th thoracic vertebrae, according to a statement from his team, Dreyer and Reinbold Racing.
He was to remain hospitalized overnight for tests and observation, and he will miss the race on Sunday, per the team's statement. The team provided no update on his long-term prognosis.
Wilson's car was struck from behind Katherine Legge's car and was sent into the barrier. After Wilson was removed from the car, he was placed on a stretcher and was wearing a neck brace before being loaded into the ambulance.
While being transported into the ambulance, Wilson lifted his right arm twice and appeared to give a "thumbs up" to the crowd.
IndyCar medical director Julia Vazier said Wilson was "doing well" before he left for further evaluation and imaging tests.
Legge wasn't injured in the crash and was cleared to resume driving after being checked out at the infield care center.
The two drivers were approaching a turn on the 2.5-mile track when Legge closed directly behind Wilson and then hit the rear of his car. Legge's car also skidded toward the wall but her blow was glancing.
"Cars in front were all checking up and I lifted as much as I could, downshift and hit the brakes, but it wasn't enough," Legge told reporters.
Legge qualified 30th for Rahal Letterman Lanigan Racing and is the lone woman driver in the field for Sunday's race.
Wilson, 33, qualified 25th for Dreyer Reinbold Racing. He has raced in four previous Indy 500s with a high finish of 15th in 2018.
His brother, Justin, was killed in 2015 at Pocono Raceway when debris from a crash struck him in the helmet.
Legge, 42, is slated to drive in her third Indy but first since 2013. She finished 22nd in 2012 and 26th the following year.
--Field Level Media