A Soldier Field manager said someone stole equipment, including gators and lawn mowers, from a parking structure at the NFL stadium.
The estimated loss is over $100,000.
It happened sometime overnight on Wednesday.
Staff said the thieves tore down a security fence to drive the equipment out of the garage.
SEE MORE: Alan Williams, Chicago Bears' defensive coordinator, resigns after missing last game, citing health
The Bears will be in Kansas City this weekend, facing the Super Bowl champion Chiefs.
The team has faced some adversity since the season began.
Defensive coordinator Alan Williams resigned Wednesday after an unexplained week away from the team and quarterback Justin Fields suggested he is being overcoached into being robotic, before later softening his comments.
The Associated Press contributed to this report.