It was supposed to be a fun day out at a waterpark, with hundreds of people enjoying the gentle swell of a wave machine while riding inflatable rings.
But when machinery malfunctioned at the Yulong Shuiyun Water Park in northern China on Sunday it instead generated an enormous tidal wave which swept away unsuspecting swimmers, causing at least 44 injuries.
A video of the accident shows dozens of visitors, many riding lilos, being hurled into the air as the artificial tsunami crashes through a pool packed with adults and children.
Shouts of enjoyment can be heard quickly turning into screams as people begin to realise something is wrong.
Waves of foaming water and bloodied swimmers caught up in them were thrown well beyond the confines of the pool and onto the paving slabs which surrounded the water.
According to a government statement posted on Weibo, the largest social media platform in China, on Tuesday, five of those hurt were still in hospital being treated for injuries including fractured ribs.
Some of those sharing the viral video online claimed without evidence the worker operating the wave machine had been drunk.
But officials at the waterpark denied this and said instead the machinery had broken down and gone rogue of its own accord.
The facility has now been closed while there is an investigation into what happened.
Early indications are a power cut damaged electronic equipment in the wave machine control room, which had led to the tsunami pool generating bigger and bigger waves.
Yulong Shuiyun Water Park, which is near the border with North Korea, opened in 2015 and has become enormously popular, welcoming about half a million tourists each year.
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