The death of a Texas woman on a Six Flags roller coaster last week is a rare occurrence, according to the International Association of Amusement Parks and Attractions, which conducts an annual injury survey of fixed-site amusement rides.

Park-goers have a 1-in-24-million chance of being seriously injured on a ride at a fixed-site park, where rides are permanently attached to the ground, IAAPA states on its website.

The 2011 “Fixed-site Amusement Ride Injury Survey,” conducted in partnership with the National Safety Council—a nonprofit membership organization that works to prevent injuries and deaths through research, advocacy, and education—also found that almost 300 million people take 1.7 billion safe rides at 400 U.S. amusement parks every year.

Six Flags Over Texas, the site of last week’s accident, closed the Texas Giant coaster from which Rosa Ayala-Goana, 52, fell last Friday evening. The park is still investigating what caused her fatal fall from the ride, according to USA Today.

A witness told the Dallas Morning News that Ayala-Goana voiced concern to a park employee that her safety restraint was not properly secured before the ride began.

Jerry Hagins, a spokesman for the Texas Department of Insurance, which regulates amusement rides in the state and conducts annual ride safety inspections, told USA Today the last inspection of the Texas Giant was good through February 2014. Park operators are also required to inspect rides daily.

“In addition to the annual safety inspection, amusement ride operators are required to inspect each of their rides every day and keep a log of those inspections,” Hagins said. “They don’t submit [it] to us, but there’s a log on premises and can be supplied to law enforcement upon request.”