(CNN) Two years after a child was decapitated on the world's tallest water slide in Kansas, investigators revealed in March that they found design flaws and unreported injuries at the site.
The death of 10-year-old Caleb Schwab and the the indictment of several people in the case has put a spotlight on amusement park safety. While the amusement park industry says its facilities are safe, just how often do accidents happen and what kind of oversight is there?
Here's what you need to know:
In 2016, emergency rooms saw 30,900 injuries associated with amusement attractions nationwide, according to the Consumer Product Safety Commission. The number of injuries for last year are not yet available, according to Elizabeth Klinefelter, a spokeswoman for the commission.
That number includes rides for both mobile and fixed-site parks. Fixed-site parks refer to permanent locations such as Disney and Six Flags while mobile parks move from one location to the next.
The commission said it's aware of 22 deaths nationwide associated with amusement attractions since 2010. That number excludes fatalities at water parks or water slides, such as the 2016 death of Caleb Schwab in Kansas.
The federal Consumer Product Safety Commission once regulated both fixed-site amusement parks and mobile carnivals.
But in the 1980s, Congress revoked that authority for fixed-site parks (such as Disney and Six Flags theme parks), allowing them to be under state or local government control. It kept federal regulation in place for mobile carnivals.
For fixed-site amusement parks, there is not one body nationally that oversees regulation -- instead that is left to state and local governments. But not every state took up regulation of amusement parks
"Currently 44 of 50 states regulate amusement parks. The six without state oversight are Alabama, Mississippi, Montana, Nevada, Wyoming, and Utah. These states contain few, if any amusement parks," the International Association of Amusement Parks and Attractions says on its website.
Amusement parks are so loosely regulated in some states, Six Flags was in charge of its own investigation in the 2013 death of a woman in its facility.
A coordinated federal effort to collect data is needed to ensure safety at amusement parks, said Tracy Mehan of Nationwide Children's Hospital in Ohio.
"Many parents either assume that the rides at amusement parks are safe and that they're being inspected, or they don't even stop to think about how safe they might be," Mehan said last year.
"So we want parents to learn in their state how rides are being inspected, by whom, and how often, so they can make the decision for themselves whether or not they want to take that risk before they go on the ride."
Congressman Edward J. Markey, a Democrat from Massachusetts, has called for greater regulation of amusement parks, arguing it would help prevent injuries.
The amusement park industry says that state regulation is the best way to handle safety. They argue that there are already many layers that keep riders safe, including mechanical and design standards, state and local governments, insurance companies and private safety firms.
Nearly 335 million people visit amusement parks in the US each year, according to the International Association for Amusement Parks.
But the likelihood of suffering a serious injury that would lead to an overnight stay at a hospital is one in 16 million, the group said last year.
The organization conducts an annual safety survey, with the latest one published last year. Its survey shows that in 2016, there were 1,253 injuries among people who went on rides. In 2015, the number was 1,508. The report does not include any fatalities, and only focuses on amusement rides on fixed sites.
"Based on the number of people that go to amusement parks each year, the relative number of injuries is, fortunately, small," Dr. Gary Smith, president of the Child Injury Prevention Alliance, said last year. "But there's still potential for serious injuries."
The International Association for Amusement Parks only collects safety data on fixed-site amusement parks. It does not provide data on amusement parks that move from one location to the other.