Park manager Laura Melling says the two had driven the ATV to the top of one of the dunes about 4 p.m. Monday when they rolled.
A St. George-area resident was killed. His passenger was transported to the hospital with injuries that didn't appear to be life-threatening.
Melling tells The Spectrum the park was very windy Monday, and that may have contributed to the crash.
The identities of the ATV riders haven't yet been released. Neither was wearing a helmet, although Melling tells The Salt Lake Tribune the vehicle had a full roll cage.
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