Most of the 18 injured suffered sprains and strains in the accident.
Fourteen people were taken to the hospital after an accident on the Wild Thing roller coaster at Valleyfair amusement park in Shakopee on Sunday afternoon, authorities said.
Four others refused medical attention at the scene, said Bill Von Bank, a Valleyfair spokesman.
A 15th person later arrived at St. Francis Regional Medical Center, hospital spokeswoman Lori Manske said. All were treated and released by 8:30 p.m., Manske said. Most of the injuries were strains and sprains, she said.
The accident happened about 4:25 p.m. as the roller coaster train was slowing as it approached the ride station. One of the cars somehow separated from the train, Von Bank said.
Bailey Merchant, 12, of Shakopee, said she was in the rear car when the middle car began jerking and smoking. She said the car "fell right off the track" and made the last car turn over.
"We were jerked and twisted, and it started to hurt really badly," Bailey said as she left the hospital.
Her mother, Tracy Theis, said a nurse at St. Francis called to tell her of the accident. "It's very scary," she said. "You don't ever want to get that phone call."
Katelyn Churchich, 16, of Oakdale, who was treated for neck and back pains, said she was in the middle car when it happened.
"It started jerking and moving around, like, not right," she said. "We kind of heard scratching, and we didn't know anything was wrong until we smelled metal grinding ... and when we looked back one of the cars was tilted on its side."
The Wild Thing will remain closed until further notice, Von Bank said. The incident will be investigated.
Nicole Triplett, 20, of Apple Valley, was with her boyfriend in the first row of the rear car. She said she must have passed out.
Triplett said the hospital staff took X-rays and told her not to go to work today because she probably suffered a mild concussion.
Wild Thing opened in May 1996. It is 200 feet high, 5,460 feet long and travels at speeds as high as 74 miles per hour.
Records show that in June 1996, its computer system stopped the ride's lift mechanism, suspending 30 passengers near its highest point for 45 minutes.
Bailey Merchant said the accident won't keep her from returning to the amusement park, "but probably not that ride ever again."
But Tripplet said she's had enough. "I will never go on a ride ever again in my life," she vowed.