The safety net that was supposed to catch her was not in place. She fell 100 feet and hit the ground.
"We're just happy she's alive. When we saw that, I assumed she was dead right there, and it's a miracle. I think it's a miracle," said the girl's father, Alex Marti.
She has 10 fractures in her back and one in her skull. Her father says she'll likely be paralyzed.
The park operator said the rides undergo safety checks every day.
Investigators say the ride operator released Marti before the safety net was in place.