A yoga class was mistaken for a "ritual mass murder" scene after members of the public saw several people lying on the floor and reported it to police.

Five police cars descended on the North Sea Observatory in Chapel St Leonards, Lincolnshire, on Wednesday night.
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"They're [students] laying down with blankets over them, their eyes are closed. It's very dark in there. I just had candles and little tea lights lit the whole room, and I was just walking around playing my drum. I had a nice floaty top on with large bell sleeves," she said.
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"I didn't know until after we left that these people phoned in saying that there was a mass murderer; they were wearing a robe and they were walking over all of the people, and it looked like some kind of ritual, and that the people on the floor were actually dead.

https://www.bbc.co.uk/news/uk-england-lincolnshire-66742339