The all-female team with the Ringling Bros. and Barnum & Bailey Circus crashed up to 40 feet (12 meters) to the floor when the rig tethering them by the hair gave way at the Dunkin' Donuts Center in Providence.
The acrobats hit the ground just after starting their "hair hang" performance and the ringmaster telling the audience, "Suspended only by the strength of ...," according to a video posted online.
The performers did not scream as they fell, but there was a "collective gasp" from onlookers who were unsure at first whether the collapse was part of the act, said spectator Aletha Wood, who was at the show with her two children and took the video.
Stephen Pare, the Providence public safety commissioner, said 15 to 20 people had been hurt, with nine treated at Rhode Island Hospital.
"They're in critical, but expect (it) to be non-life-threatening injuries, a lot of broken bones, etc.," he told reporters.
A hospital spokeswoman gave different numbers, saying 11 people were treated in the emergency room and seven were admitted.
The women fell between 25 and 40 feet (8 and 12 meters), and a performer on the floor was also badly injured, fire officials said.
Wood said the collapse stunned the audience.
"It was a pretty packed house," she said. "There was a metal disc hanging from the ceiling and it looked like it was being held by a single cable."
Stephen Payne, a spokesman for Feld Entertainment, the parent company of Ringling Brothers, said that because the performers were attached to the equipment and could not let go of it, a safety net was not required.
SEQUINED COSTUMES
Wood's video showed the equipment and the performers at the start of the show hidden by a cloth cover lit by blue and red lights.
The cloth fell away to reveal the acrobats dressed in sequined costumes and hanging from a circular canopy apparently suspended by a cable. One of the performers was suspended beneath the rest.
The structure then suddenly crashed to the floor. Workers and emergency personnel rushed to the acrobats, with a gurney arriving a couple of minutes later after lights were dimmed.
The Labor Department's Occupational Safety and Health Administration said in a statement that its inspectors were at the scene to determine if there had been any violations of safety standards.
Payne, the Feld spokesman, said the company was working with authorities and its safety team to find out what happened and to make sure the apparatus was safe.
"Safety is our top priority, not just for our performers but also for our crew and all the families who come to see a Ringling Bros. performance," he said in an email.
Ringling's other two shows for Sunday were canceled, along with the 10:30 a.m. show on Monday.
Lee Kaplan, a product liability lawyer in Houston, said the fact that hundreds of spectators witnessed the accident opened up the possibility of claims being filed on behalf of children who could have been traumatized.
Kaplan said possible defendants ranged from the circus to the maker of the apparatus. He said performers often signed waivers that would limit their ability to sue the circus.
Tom Lyons, a Providence lawyer, said injured performers could file a workers compensation claim against the circus. If a defective product was involved, they may have a claim against the manufacturer, he said.
In 2011, Feld Entertainment paid $270,000 to settle charges by the Department of Agriculture that Ringling animals were mistreated.
The American Society for Prevention of Cruelty to Animals agreed in 2012 to pay $9.3 million to Feld Entertainment to settle a lawsuit brought by the company in response to dismissed legal claims that Ringling mistreated elephants.
