No explanation has yet been given for the Tri-State Auto Auction employee's bizarre behavior, which broke several people's bones, and left several in need of major surgery.
Eyewitnesses said the SUV was lining up for display on Wednesday morning, but suddenly accelerated, ramming into a minivan which crushed several people against a wall, before turning and speeding out of an exit into another crowd outside the venue.
A clerk at the auction told the Southtown Star: "The Range Rover accelerated very quickly... It hit the van from behind, shattered the glass and it pinned some people down."
Another eyewitness said: "People were crying and screaming. It was a very emotional scene."
Auction attendee Mohaned Bustami, 28, who was hit by the SUV while examining an on-sale minivan, currently has no feeling below the neck, and injuries to his face and back.
"He was not even talking, he was just moving his eyes," his brother told the Chicago Tribune.
Their uncle, who was also hit, now has a dislocated hip and is facing at least five operations.
A Chicago resident was also severely injured in the incident, the Tribune said. His daughter said he now has several broken ribs, a bruised kidney, and possible spine damage.
The company running the auction has not yet commented on the incident. Local police chief Tim Sulikowski said the reason for the sudden acceleration is unknown.
