Thornbrue, known to his friends as Sammy Brue, said he was playing to a crowd of 40 people, which included actor Tony Danza.
Unfortunately, Thornbrue didn't have a permit and the police told him and his father, Mike Thornbrue, to close up shop.
"We got busted, but Tony Danza made the cops let him play one more song," said Thornbrue's father Mike, during an interview with The Park Record. "It looked like the officers felt bad shutting him down, but they were just doing their job."
However, the little incident proved beneficial for the young musician.
"After they told me to pack it up, I went down to the Filmmaker Lodge (down the street to wait for my friend Nathan Osmond," Sammy Thornbrue said. "They let me in and escorted me to the stage."
Thornbrue played the Sundance Filmmaker Lodge in the Elks Building, 550 Main St., and at the Fender Music Lounge at 780 Main Street.
"This is my first time to play up here during the film festival, even though I've played up here since July," Thornbrue said. "I just wanted to come up here and see what I could do. And to play the Fender Lounge and the Filmmaker Lodge was, wow!"
Thornbrue has been playing acoustic guitar for about a year. He also plays banjo and electric guitar, but prefers the non-electric sound.
"I first got an electric guitar, but when I got an acoustic guitar, it was better all around," he said.
The musician plays a small-body, OM-model Loar guitar.
"I wanted to play the Loar because Justin Townes Earle plays one and they also sponsor me," said Thornbrue, who also cited the roots-music quintet the Avett Brothers, singer and songwriter Joe Fletcher and Americana band Old Crow Medicine Show as his musical influences. "I like it because it's easier for me to manipulate, but when I upgrade I would like to get a Gibson."
Even before he was in elementary school, Thornbrue wanted to play the guitar.
"I wanted to play the guitar because I wanted to inspire people," he said. "It inspires me and I wanted to share that feeling."
So far, Thornbrue has nearly 20 songs in his repertoire, and nine of them are originals.
"When I write songs, I just start playing and then put together some runs in between the chords," he said. "I don't really practice the runs. I just play what sounds good to me."
Although the young fingerpicker practices every day, he does have a weakness video games.
"The hardest thing for me when I know I have to practice is that I have a computer and XBox at home," he said with a laugh. "I have to stay away from those or I won't practice."
Thornbrue can be seen occasionally playing at a venue called Mojo's in Ogden and other festivals and parties.
"My goal is to play a lot of other places and eventually open for the Avett Brothers," he said.
For now, he's excited to busk on Main Street for the rest of film festival week, so, he and his father are going to get a permit.
"Permits are $15 a piece and we have to request them from Park City," Mike Thornbrue said. "We tried to get one last week, and were informed that they weren't handing any more out, but when the officers shut us down, one of them gave us her card and told us to go request another permit and said if they wouldn't give us one, then she said she would call them personally."
On Monday, Mike Thornbrue said that the Sundance House may have his son play sometime this week.
"We come from a long line of loggers, truckers and railroad workers from the Oregon Coast and my grandfather is on old pioneer who settled in Lincoln City," Thornbrue said. "We're taking the guerilla path with Sammy's music. We just go out and do it and then hang on for the ride. So far, this has been a fun trip."
For more information about Sammy Thornbrue and his music, visit www.sammybrue.com .