(CNN) A group of shoppers in Wales said they were terrified when they became trapped in a malfunctioning shopping-center elevator that rose and plunged repeatedly at a higher-than-usual speed.

"It would go up to the top floor and just drop as if nothing had control over it," Taris Chapman, 18, told CNN about the incident Saturday evening at St. David's shopping center in Cardiff.

A spokeswoman for South Wales Fire and Rescue Service, which responded to the incident, said no one was visibly hurt and no ambulance was involved.

Around a dozen people were affected, Chapman wrote in a Facebook post, adding that the elevator was "just plunging us down seven floors with force whilst jolting."

She told CNN she was stuck for up to 35 minutes with her three friends.

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