Twenty-two people were aboard the Sol Spin ride when it stopped mid-cycle. Riders were stuck in the air for nearly two and a half hours.
The ride was stuck in a horizontal position, with some riders seen leaning sideways. None appeared to be hanging upside down.
Mechanics were eventually able to crank the ride down.
"We followed the ride manufacturer's and Knott's emergency procedures to safely evacuate the 22 guests by 4:30," a statement from Knott's Berry Farm read.
Two women were treated and released from the hospital.
Cal/OSHA's Amusement Ride and Tramway unit is now leading the investigation.