This isn't a criminal onslaught. It's the Rage Room.
And it's smashing its way to success in Serbia one angry visitor at a time.
"This feels so good!" Duvnjak said sweating and panting, as he admired the mound of debris he created — for just a modest fee.
"I feel I let go of all my negative energy," the 18-year-old gushed. "This last year was a tough one and I wanted to end it with a bang!"
Since it opened in the northern Serbian city of Novi Sad in October, the Rage Room has drawn a flurry of attention in the Balkan country where two decades of war, political crisis and economic hardship have driven many people over the edge. Inspired by a similar "Anger Room" in Dallas, Texas, Serbia's version was set up by two teens who saw the U.S. original online and figured it could be a way to earn pocket money.
"On average, we have one person a day, enough to keep us going," said Nikola Pausic, an 18-year-old who runs the room with a friend.
The Dallas version costs up to $75 per session and has an array of objects to destroy, including computers and office furniture. Serbia's Rage Room, organized in a refurbished garage, is much more basic — and cheaper.
Included in the roughly $6 fee is the right to smash a chair, a table, a bed, a coat-rack and a book-shelf, along with items such as framed photographs, empty cans and plastic containers. Clients must wear a helmet, protective glasses and gloves. Afterward they get to unwind to relaxing music, leaving the clean-up to staff.
"Dozens have come so far," Pausic said, "people of all ages" — adding that it's also popular among women. He said that visitors usually need about five minutes to destroy everything inside.
While it may be an easy way to let off steam, experts warn that projects like this are no replacement for anger management therapy.
Sanja Marjanovic, a psychologist from Belgrade, said that modern science looks for ways to control frustrations before they explode into full-blown rage. She explained that "venting anger does give you an immediate sense of relief but in the long run, one becomes accustomed to feeling angry."
"In a stressful situation, one can count to ten, or take calm, deep breaths," she said. "It's much more useful to practice yoga."
Pausic said each visitor must sign a document that includes a clause saying the Rage Room does not aspire to offer medical assistance.
And, after the session is over, customers are given a CD that includes information about professional therapists and how to contact them.
For his part, Duvnjak found therapeutic value in the Rage Room. He said the session helped to take off some of the pressure that had built up in his studies — adding that many of his friends felt the same way.
"This is better than getting into a fight," he concluded.