"Kids were on the front row and there were people screaming.
"She was yelping in agony, it was traumatic as she bounced as she hit the floor. There was an announcement after a min or two to all leave."
A different witness told The Sun Online: "It was horrific. I thought it was part of the act but when she didn't get back up I knew something was wrong.
"A group of people ran on to help her and people were shouting for a paramedic.
"But it looked terrible. People in the audience were coming out crying. There were quite a lot of kids as well."
The person added: 'I thought I heard her scream or wail, so hopefully she is conscious.
A spokesman for Zippos Circus said: "The female British artist, Jackie Armstrong, performs an aerial act and is a highly experienced circus artist with 10 years in the ring.
"Jackie was immediately attended to on the scene by first aiders and an ambulance called. She was taken to hospital by ambulance and further information on the nature of her injuries is awaited."
Following the incident, audience members were asked to leave the Big Top and offered tickets for the next performance that evening.
Circus Founder and Director Martin Burton told MailOnline: "Jackie is a very experienced artist whom we value dearly as part of our circus family.
"Clearly we are concerned and offering her and her family our full support and sympathy at this time.
"At this stage, we cannot comment further as we have no information on any injuries she may have sustained."
