Hackers hijacked an electric billboard in a busy shopping centre - and showed pictures of Swastikas and a Shariah Law "warning" to passers-by.
The 30ft TV screen advert was taken over by while the busy streets were filled with shoppers and children enjoying the school holidays.
Thousands of shoppers witnessed the bizarre scenes in Cardiff's main shopping district as a series of at least eight pictures flashed up on the large screen.
The images included a Nazi Swastika and a hoax Islamic extremist "warning" which read: "This is a Sharia controlled zone. No alcohol, no gambling, no porn."
The billboard also showed a cartoon drawing of President Donald Trump with a face of a frog and a sinister "Big Brother Is Watching You" sign from George Orwell's dystopian novel 1984.
An anonymous group later claimed to be behind the attacks, with users on social media saying they "had a little fun" with the billboard.
A poster on internet site 4chan wrote: "As you can see, they had a little fun."
The screen above the Superdrug store on Cardiff's Queen Street was shut down by controllers BlowUP Media on Tuesday night and remained unplugged today.
The company released a statement saying: "Our team are trying to find out what happened."
South Wales Police said they received a number of calls from the public and are considering whether to launch an investigation.
A spokesman said: "We alerted the city council and will investigate any crimes which may have been committed."