Last Updated May 5, 2014 11:23 AM EDT
PROVIDENCE, R.I. -- Investigators looking into why eight circus acrobats plummeted to the ground during a U.S. aerial hair-hanging stunt have found that a clamp snapped, a public safety official said Monday.
"We have identified a clamp that snapped that held them to the rafters, and it failed," Providence Public Safety Commissioner Steven Pare told WPRO-AM a day after a support frame collapsed during the Ringling Bros. and Barnum and Bailey circus.
Three of the acrobats remained in critical condition Monday morning. Several performers on the ground also were injured. None of the injuries appear to be life-threatening, according to Stephen Payne, a spokesman for Feld Entertainment, the parent company of Ringling Bros.
Nine performers were seriously hurt during Sunday's performance at the Dunkin' Donuts Center in Providence, including a dancer below. Several others also suffered less serious injuries.
The act is part of the "Legends" show, during which performers hang "like a human chandelier" using their hair. Eight of the injured were members of the same circus troupe, and are from the United States, Brazil, Bulgaria and Ukraine, according to the circus's website.
"They've used this act many times. Unfortunately this particular clamp failed. It snapped off. We have it, we're analyzing it, we're seeing why it happened to ensure it doesn't happen in the future. That's all part of our focus," Pare told WPRO.
Investigators from the federal Occupational Safety and Health Administration are probing the accident, along with local authorities.
The accident was reported about 45 minutes into the circus' 11 a.m. Legends show. It was witnessed by an audience of about 3,900, many of them children.
Payne said earlier the metal-frame apparatus from which the performers were hanging came free from the metal truss to which it was connected. The eight women fell 25 to 40 feet, landing on the dancer below.
There was no net underneath to catch them, reports CBS Providence affiliate WPRI-TV.
"I screamed. I'm like, that's not right," Chelie Barrie, of Mystic, Connecticut, told WPRI. "Sometimes you're surprised and it's part of the show but this clearly wasn't. It's quite a shame."
Rhode Island Hospital in Providence admitted 11 patients with varying injuries, including one in critical condition, spokeswoman Jill Reuter said Sunday.
Performers Dayana Costa, Julissa Segrera and Stefany Neves were in critical condition Monday morning, Reuter said. Viktoriya Medeiros and Viktorila Liakhova were listed in serious condition, while Samantha Pitard, Svitlana Balanicheva and Widny Nevas were listed in good condition.
The names and conditions of three others injured in the accident had not been released.
Roman Garcia, general manager of the Legends show, asked people to pray for the performers.
"Everybody's doing fine, everybody's at the hospital, everybody's conscious, everybody's doing pretty well," he said at the Dunkin' Donuts Center less than two hours after the accident.
The hair-hanging stunt is described on the circus' website as a "larger-than-life act" featuring eight female performers.
Payne said all the performers have been doing "some variation of this act for some time," though he didn't know how long. The current incarnation of the act began in January with the launch of the show, he said.
"These 'hairialists' perform a combination of choreography and cut-ups including spinning, hanging from hoops, and rolling down wrapped silks, all while being suspended 35 feet in the air by their hair alone," the website says. "In this hair-raising act, audiences will even see the weight of three girls held aloft by the locks of only one of these tangled beauties."
Video taken by audience members shows a curtain dropping to reveal several performers hanging from an apparatus suspended from above. Seconds later, as they begin to perform, the women fall, and the metal apparatus lands on them.
"It just went crashing down," said audience member Sydney Bragg, 14, of North Kingstown. "Everyone was freaking out. We heard this huge clatter and then we just heard the girls scream."
She said spotlights were on the performers at the time, but all the lights went out after the fall.
Rosa Viveiros of Seekonk, Massachusetts, said she saw that the acrobats had fallen on top of at least one other performer below, a man who stood up with his face bloodied. The acrobats remained still and did not get up, she said.
"We thought it was part of the circus," said her husband, Joe.
The couple attended the circus with their 6-year-old grandson and 9-year-old niece.
"Everyone was in shock," Rosa Viveiros said. "It was pretty overwhelming to see that."
The Ticketmaster website says the circus is moving to the XL Center in Hartford, Conn., where performances are scheduled to begin on Thursday.
Feld Entertainment said in a news release that they "appreciate everyone's thoughts and prayers for our performers, and we are sharing all of those with them as they recover."
A Ringling Bros. aerial performer was killed in 2004 in St. Paul, Minnesota, when she was twirling 30 feet in the air on long chiffon scarves and the material gave way.