Prince George's County Fire officials say it took about five hours Sunday to rescue 17 adults and seven children from The Joker's Jinx roller coaster.
Assistant Fire Chief Paul Gomez says the riders were sitting upright. A few had cramps, back pain and dehydration, but there were no major injuries.
A Six Flags America spokesman said in a statement that it is not yet clear what caused the ride to stop but that it has a computerized safety system that "performed as it is designed to."
Six Flags's website says the ride goes 60 m.p.h. and upside down four times.
Earlier this month, a Six Flags roller coaster in New Jersey lost power, forcing its riders to walk all the way down from its first hill.
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