Hundreds of teenagers have attempted to “speed run” Scientology buildings in different parts of the UK as part of a TikTok trend that started in Los Angeles.

Scientology speed running is where people rush into churches and see how far they can get before being ushered out by staff. The Church of Scientology said using its church spaces for viral stunts was “trespass, harassment, and disruption of religious facilities”.

A single post on Snapchat last week about a London run snowballed. First UK raid of Scientology. Happening this Saturday 2nd May. Bring face coverings and GoPros. Spread the word,” it read. The post was shared on TikTok and by Saturday about 100 people were laying siege to London’s main Scientology church near Blackfriars.

Rizak Abdullahi, 19, who watched the events unfold, said: “Some of them were dressed as dinosaurs, some had cat masks, it was quite funny.” He said by the time the group had gathered, two City of London police vans were waiting to rebuff them. “You know the UK police, they know everything,” Abdullahi said.

City of London police said officers spoke to the crowd, who left after a short while. No arrests were made.

Levi Telford, 16, who had come to London from Carlisle – a four-hour trip – to join in said that aside from the “mysterious” nature of Scientology, the trend itself was enough of a reason to go. “I think people want to do it here just to be part of the trend, to be part of something,” he said.

The speed run trend began at the end of March with a TikToker called Swhileyy, who posted a video showing him running through the lobby of the Church of Scientology’s LA headquarters. After gaining 90m views, the video was deleted.

Scientology churches in Vancouver and New York were raided next by young people competing to see how far they could get.

For some, the idea was to map out the insides of the buildings, learning more and more each time they went. Others attempts were more overtly surreal: one person ran in dressed as Jesus; a group dressed as Minions attempted entry, saying they were looking for Tom Cruise.

Videos of Scientology speed runs have gathered millions of views online, and this weekend copycats began to appear in the UK. A group of 30 or so teenagers tried to speed run a Scientology church in Edinburgh but were also rebuffed by the police. Drenched by rain, the group took refuge in a Greggs and then went home.

Alexander Barnes Ross, who has led protests against Scientology in the UK, expressed concern about the speed runs. Having spent the last year fighting for the right to protest outside Scientology buildings, he said this trend “risks giving the church an opportunity to reopen the case.”

While he welcomed any efforts to expose what he described as “harmful practices” of the church, he said: “There is nothing funny about Scientology. This is a dangerous, harmful organisation.” He said attempts to break in with force undermined his peaceful efforts to protest.

But the people involved insist speed runs are done in the spirit of fun and curiosity. “It’s so secret that people just love to find out what’s happening and explore,” said a TikToker called Hiddenurbex, who went to the London speed run with his friends.

The Church of Scientology said individuals had repeatedly forced their way into church locations, damaging property and endangering staff. It said it was reviewing “all available remedies” to protect personnel, visitors and property.

It said: “The church welcomes lawful visitors. It does not welcome mobs forcing entry, damaging property, disrupting religious spaces or endangering people for views.”