In 1993, two trains collided at low speeds in the station of the Six Flags Great America ride causing eight people to be injured.

A major incident on the Six Flags Great America version of Demon occurred on Saturday, April 18, 1998.
Twenty-three riders were left stranded upside-down after the black train came to an unexpected halt in the middle of one of the vertical loops.
Firefighters used a cherry picker to bring the passengers to safety.
Some riders were stuck for nearly three hours.
Three passengers were taken to local hospitals out of precaution but released that afternoon.
Investigators concluded that the incident was caused by mechanical failure.
A guide wheel that runs along the inside of the track separated from the axle of the last car.
A mechanical safety system built into the wheel assembly engaged, preventing the train from derailing.
The roller coaster reopened shortly after the conclusion of the investigation.
In 1993, two trains collided at low speeds in the station of the Six Flags Great America ride causing eight people to be injured.
A major incident on the Six Flags Great America version of Demon occurred on Saturday, April 18, 1998. Twenty-three riders were left stranded upside-down after the black train came to an unexpected halt in the middle of one of the vertical loops. Firefighters used a cherry picker to bring the passengers to safety. Some riders were stuck for nearly three hours. Three passengers were taken to local hospitals out of precaution but released that afternoon. Investigators concluded that the incident was caused by mechanical failure. A guide wheel that runs along the inside of the track separated from the axle of the last car. A mechanical safety system built into the wheel assembly engaged, preventing the train from derailing. The roller coaster reopened shortly after the conclusion of the investigation.
Demon (roller coaster)