A Rhode Island public safety official says a snapped carabiner is the only piece of equipment investigators have found that failed in a circus accident in which eight aerial acrobats plummeted to the ground.

Providence Public Safety Commissioner Steven Pare stopped short of saying the broken clip was the cause of Sunday's accident at the Ringling Bros. and Barnum and Bailey circus. But he says, as of Monday afternoon, it's the only piece of equipment investigators have identified that failed.

Pare says they still don't know why it snapped.

He says the carabiner is a national name brand, although he did not have the manufacturer's name.

Two of the performers are in critical condition. The women suffered injuries including a pierced liver and neck and back fractures.