Rachael Hamblin, of Wales, Utah, died after careening off a road and into the rocky, fast-flowing Pleasant Creek, which is just east of Pleasant Creek Canyon. Sgt. Greg Peterson of the Sanpete County Sheriff's Office said the pair had been turning a corner when they lost control.

Both of the girls were trapped beneath the vehicle when it fell into the water. Hamblin was washed about 200 yards down the rushing stream and did not survive, according to Sanpete County Sheriff's deputies.

The other teenager was able to free herself, and later arrived at the Sanpete Valley Hospital in serious condition.

Hamblin would have been 18 the next day, said her father, Carl Hamblin. Neither of the girls was wearing a helmet.

- Ana Breton, Nate Carlisle and Steve Gehrke