Twenty-three people, mainly children, were injured earlier this month when a Yo-Yo ride collapsed at a county fair in California, USA.

The ride has chairs attached by chains to metal arms, which extend from a rotating hub. Those who witnessed the incident reportedly said that the arms and chairs suddenly collapsed, dragging the riders along the ground until it came to a stop.

The Associated Press reports that an initial investigation believed that a mechanical failure in the hub caused the chairs to collide with one another and the chains subsequently became tangled.