Jake Siebenlist knocked over a glass display case and hurled objects across the room at the Stampede gallery, according to police.

During an otherwise normal day at the Denver Art Museum on Sunday, 18-year-old Jake Siebenlist pushed over a glass display case full of artifacts and shattered it before pushing museum patrons out of the way en route to other works of art, which he threw across the room, according to the Denver Police Department.

Some pieces were Native American, others were Mayan and some were Chinese. At least one dates back to between 250 and 450 AD, according to the museum website. Ten pieces were damaged or destroyed in all, according to a police statement.

“This was a visitor,” said Christoph Heinrich, director of the Denver Art Museum in a press conference Monday morning. “He bought a ticket, so it was totally unpredictable that something like this could happen.”

The incident occurred at 1:47 p.m. on the fourth floor of the Stampede Art Gallery, a wing dedicated to the role of animals in art.

After pushing museum goers out of the way, “Siebenlist then began to throw numerous sculptures across the room causing them to break and began shattering other art sculptures into the ground,” according to a probable cause statement. “Siebenlist also tried to damage two paintings that were protected by plastic glass, but was unable to cause any damage to the two paintings.”

Security guards restrained Siebenlist, who tried to punch one guard, before police arrested him, the statement said.

Denver police redacted information about how much the destroyed art is worth. It will be a while before a valuation is complete, Heinrich told Denverite. It takes time and money to have the museum’s conservators assess the works of art.

We don’t know the motive and DPD said they cannot reveal any additional information until after the investigation is complete.

These were the pieces damaged and destroyed in the incident: