The AP reported that Sergeant Christopher Cook told that the police believes the woman fell on Friday at Six Flags Over Texas in Arlington, and there was no foul play involved.
The Park spokeswoman Sharon Parker told that a woman died while riding the Texas Giant roller coaster, which is dubbed as the tallest steel-hybrid coaster in the world. But she did not specify how she was killed.
Some witnesses said the woman who died wasn't properly secured.
"We are committed to determining the cause of this tragic accident and will utilise every resource throughout this process," Parker said in a statement yesterday. "It would be a disservice to the family to speculate regarding what transpired."
Cook said that the police, fire and emergency medical services reached the park at around 6:45 pm Friday for a woman who had fallen from a train car while riding a roller coaster but she was pronounced dead at the scene.
Carmen Brown told The Dallas Morning News that she was waiting in line to get on the Texas Giant when the accident happened and witnessed the woman being strapped in.
"She goes up like this. Then when it drops to come down, that's when it (the safety bar) released and she just tumbled," Brown, of Arlington, told the newspaper. "They didn't secure her right.
Six Flags said the ride will be closed as the investigation continues.
The Texas Giant is 14 stories high, and has a drop of 79 degrees and a bank of 95 degrees. It can carry up to 24 riders. It first opened in 1990 as an all-wooden coaster but underwent a USD 10 million renovation to install steel-hybrid rails and reopened in 2011.