All 24 people aboard a spinning carnival ride were hurt as the machine collapsed on Friday night.

The incident happened at about 6 p.m. Friday, when the carnival ride called the Yo-Yo collapsed at the Calaveras County Fair and Jumping Frog Jubilee, located at about 80 miles southeast of Sacramento.

The collapse of the ride’s center pole caused the metal arms, each with a seat at the end attached by a chain, to crush back toward the center as they were spinning, according to Dennis Townsend, a chief in the Calaveras County unit of the California Department of Forestry and Fire Prevention, The Associated Press reported.

Those aboard the ride were hurts as they hit the ground or other parts of the structure. Most victims were children.

Three victims were badly injured and airlifted one each to UC Davis Medical Center in Sacramento, Doctors Medical Center in Modesto and Memorial Medical Center in Modesto. The extent of their injuries is unknown at the moment, said Sgt. Dave Seawell, a spokesman for the Calaveras County Sheriff's Department.

Three other hospitals in the area received fifteen injured, mostly were taken there by ambulances and some were taken by their friends or relatives who had cars.

Five injured were taken to Mark Twain St. Joseph's Hospital. Most of them complained about knee pain, said Jessica Norris a hospital spokeswomen.

The California Occupational Safety and Health Administration is initiating an investigation into the accident, said Lisa Williams, a spokeswoman for the California Department of Forestry and Fire Protection.