A 10-year-old Nevada boy's birthday party ended in horror after he plunged 20 feet from a zipline onto a concrete floor.
The child, called Knox, sustained a concussion after the fall from the aerial attraction at Spy Ninjas in Las Vegas.
Sickening video taken of the incident on February 7 and obtained by Inside Edition showed the moment the boy plummeted as eye witnesses screamed below.
The clip showed Knox appearing to test his weight before stepping off the platform and letting his harness carry him along the line.
But just seconds later he dropped from the sky, landing on his back according to his family.
'Oh my god!' someone screamed as Knox could be heard moaning in pain.
'Calm down, baby, calm down,' his Uncle Navonte Hill, who shot the video, could be heard saying off camera. 'Breathe, baby. We need an ambulance.'
Several adults told Knox to 'stay still' while he cried out in pain as they waited for medical personnel.
Knox was celebrating his birthday at Spy Ninjas in Las Vegas when he fell off the zipline ride and plunged 20 feet
Just moments after stepping off the platform, he was seen plunging to the ground with his harness still attached to him
Hill told Inside Edition it was the 'scariest moment' watching his nephew fall so far from the ground.
'It seemed like it was in slow motion,' he told the outlet.
The family doesn't know what went wrong, but believe it was some kind of harness malfunction.
Off-duty nurse Stacy Houston was there to celebrate a different birthday party and was able to help the family until emergency services arrived, Hill told 8 News Now.
'It was just chaos,' Houston told the outlet. 'I was stabilizing the C-spine, holding his head in place.'
Houston said the spot Knox fell was the best area to fall, as there was nothing underneath him, like arcade games.
'Had he broken just five seconds later, he would’ve tumbled into those arcade games, and it would’ve been a completely different point of breakage,' she told the outlet.
Knox is expected to make a full recovery. The Daily Mail has reached out to the family for comment.
His Uncle Navonte HIll, who filmed the incident, said the boy suffered a concussion
An off-duty nurse was able to help Knox until emergency personnel showed up
Spy Ninjas said in a statement: 'Nothing matters more to us than the safety and well-being of our guests.'
The company said its staff 'responded immediately' and followed protocol.
The zip line has temporarily been closed done and staff will undergo recertification.
'Our entire team wishes them a full and speedy recovery,' Spy Ninjas said to Knox's family.
