THIS is the terrifying moment a human cannonball is seriously injured after bouncing off the safety net and slamming into the ground.

Chachi Valencia, known as the Rocketman, crashed down to earth in front of crowds at the Riverside Country Fair in Indio, California.

One onlooker captured the moment the stunt went horribly wrong.

Footage shows Chachi – who performed at the London Olympics closing ceremony – shoot from the barrel of an giant cannon, clad in a red and yellow jumpsuit.

His daring flight sees him loop high above the concrete square which is filled with food vans and fairground rides.

The stuntman twists midair onto his back as he nears the awaiting landing net.

But this is where it all goes wrong.

Instead of landing in the centre of the net, Chachi crashes into the far corner – almost missing it altogether.

The elastic net boings him back into the air and sends him spinning off the side.

Screams of horror ring out as the man rag-dolls towards the ground.

The Rocketman smacks into the solid concrete and crumples in pain.

Concerned crew workers rush to the side of the injured stuntman, who is not moving.

Sseveral of Chachi’s ribs were shattered by the incident, his wrist was broken, his liver lacerated – and he needs knee surgery.

After the terrifying cannonballs-up, Chachi told KESQ that a sudden gust of wind had pushed him off the right flight path.

He said: “I knew I was going to land off to one side. After that, I really don’t remember anything.”

“The next thing I remember, I was in the ambulance and the medic was asking me questions.”

Chachi was only fifteen minutes into his routine when the accident happened.

A GoFundMe page set up to help pay his medical bills said the “road to recovery will be long”.

Donors have already contributed over $10,000 to fund his treatment, which may include surgery within the next week.

The plea says: “We’re asking for your support to help Chachi cover his medical expenses, rehabilitation costs, and lost income during his recovery.

“Every contribution, including your thoughts and prayers and sharing this link will make a real difference in his life and help him get back on his feet – and get him back flying through the air!”