Dozens of tourists were injured after a massive wave came crashing down on them in a "tsunami pool" in northeast China, according to Chinese media outlets.

City officials from Longjing announced that 44 tourists were injured in the unexpected swell, and that the pool is closed for investigation, the South China Morning Post reported.

A viral video of the incident shows hundreds of people inside the wave pool at the Yulong Shuiyun Water Park, when an immense surge of water builds up near the back of the pool and slams down on the people inside.

The wave was forceful enough that it pushed huge volumes of water over the edge of the pool, prompting bystanders to rush away from the edge.

Though rumors circulated that the wave operator had mistakenly set the wave controls to the maximum setting, the South China Morning Post reported that it was likely a power issue in the control room.

"According to the initial stages of the investigation, the incident was caused by a power cut that damaged electronic equipment in the tsunami pool control room, which led to the waves in the tsunami pool becoming too big and injuring people," a Longjing city announcement said, according to the South China Morning Post.

China Daily reported that the incident occurred Monday afternoon, and 39 of the injured tourists were discharged from local hospitals by 5:00 pm on Tuesday local time.

The news outlet reported that the remaining five people remained at the hospitals due to rib or foot fractures.

This article was originally published by Business Insider.

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