The filming intensifies for the fourth season of BBC One's "Sherlock," as men with high-powered guns and a roving helicopter were spotted on St. Catherine's Island near Tenby.

Wales Online reported that several action-packed scenes for "Sherlock" season 4 caused commotion on the small tidal island in Pembrokeshire, Wales.

The crowds present in the area said that they saw a helicopter draped in a Moriarty flag hovering over the island while heavily armed men wearing black wardrobe were scattered all over the place.

Fans of the crime drama series stayed within the vicinity in hopes of seeing the show's lead star, Benedict Cumberbatch, who portrays the role of the legendary detective Sherlock Holmes.

Members of the Pembrokeshire Council were excited as they welcomed the people behind the hit series.

"Our county always looks good on film and I've no doubt the exposure it will receive will boost visitor numbers in the future," the council's cabinet member for transportation and major events Rob Lewis said. He added that as a fan, he is looking forward to how the series will feature the island on TV.

The production was earlier seen all over the Charles Street area in Cardiff, where they created a Christmas set-up.

Meanwhile, Tom Hiddleston remains mum about his rumored involvement in "Sherlock" season 4 despite the claims that he will portray the role of Sherlock's other brother Sherrinford.

But the possibility of the actor's appearance on the show looks dim, since he will be busy making several films with the Marvel Cinematic Universe as Loki, including next installments of "The Avengers" and "Thor." He is also rumored to replace Daniel Craig as the next lead star of "James Bond."

In other news, "Outsourced" star Sacha Dhawan was tapped to portray a new character named AJ when "Sherlock" returns for season 4 next year.