A horror crash which took place in front of a packed big top crowd on Monday will be investigated by safety officers from Ipswich Borough Council.

The incident happened at Uncle Sam’s Great American Circus in Chantry Park, Ipswich, when two motorcyclists collided at the top of a cramped, spherical cage and dropped to the ground.

They were taken to Ipswich Hospital and are both believed to now be in a stable condition.

The Wall of Death-style spectacle, known as the Thunderball, sees riders use centrifugal force to send themselves spinning around the inside of a cage.

It is described on the circus’ website as “death defying”.

Following the crash, which happened when the stunt men were at the top of the sphere, the emergency services were called to the scene and the big top in evacuated.

Suffolk Constabulary later decided it did not need to investigate the incident but the borough council will now be looking into what happened.

A spokesman for the council confirmed it had been made aware of what happened and would be examining the circumstances surrounding the crash.

On Monday an East of England Ambulance Service spokesman said: “One rider suffered a head injury and one had upper body and leg injuries. Both were fully conscious and neither were critical.

“Neither are thought to be in a life-threatening situation.”

Michael Nanton, 49, and Sue Padmore, 51, from Ipswich, were among the crowds at the circus show when the accident happened just before the interval.

Mr Nanton said: “It was scary to see it happen.

“The bikes crashed, the motorcyclists fell and landed underneath the bikes. The organisers asked if anyone in the audience had medical training or was a paramedic to assist them.

“Then we were evacuated straight away and they gave people half their money back.”

The circus, which has been unavailable for comment, has now moved on to its next engagement in Chelmsford.