PROVIDENCE, R.I. — Investigators looking into why eight circus acrobats plummeted to the ground during an aerial hair-hanging stunt have found that a clamp snapped, a public safety official said today.

“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 this 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.

“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.

The act is part of the “Legends” show, during which performers hang “like a human chandelier” using their hair.

Investigators from the federal Occupational Safety and Health Administration are probing the accident, along with local authorities.

Eight of the injured were members of the circus’ Medeiros troupe and are from the United States, Brazil, Bulgaria and Ukraine, according to the circus website.

A spokesman for Rhode Island Hospital said performers Dayana Costa, Julissa Segrera and Stefany Neves were in critical condition this morning. 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.

The accident was reported about 45 minutes into the circus’ 11 a.m. Sunday performance at the Dunkin’ Donuts Center. It was witnessed by an audience of about 3,900, many of them children.

Payne said the metal-frame apparatus from which the performers were hanging came free from the metal truss to which it was connected.