The cast member, Mariia Konfektova, was twirling around on her aerial hoop during Saturday night's Cirque du Soleil show at the Portland Exposition Center in Oregon.

Check out the footage ... Konfektova suddenly loses her grip on the large hoop and flips around in the air, before falling hard to the ground. Her head bounces off the floor and she looks around in a daze.

People rush to her aid as the video cuts off.

Konfektova and her teammates are known to not use a net during their stunts, adding an extra element of high danger.

One observer at the performance, Benjamin Goldstein, told ABC News he thought the mishap was all part of the show at first -- but then he saw blood gushing from her nose and knew something went seriously wrong.

Goldstein said Konfektova gave a thumbs-up as people were assisting her onstage -- and then she was taken to the hospital for treatment.

Cirque du Soleil later issued a statement saying Konfektova was “conscious, stable, and being cared for by medical specialists and [their] team.”