A pane of glass from a wall on the Valley Performing Arts Center broke Saturday afternoon.

The damage occurred during the first performance of “The Nutcracker” at around 1:45 p.m., said Mike Bergantzel, manager of facilities for the VPAC.

Bergantzel said the cause for the breakage is unknown.

“It just broke spontaneously,” he said.

The broken window is from west side of the building, which is made almost entirely of glass. The entirety of a 5 by 6 square foot pane was damaged.

A new window assembly will be ordered from the manufacturer and take three to four weeks to be ready, Bergantzel said. When the new glass arrives to the VPAC, it will take about a day to replace the old one, which sits about seven feet off the ground.

The glass on the west wall of the VPAC is safety glass, which is similar to what it is found in cars, Bergantzel said. If the glass breaks, a plastic membrane keeps it from separating and falling to the ground.

Bergantzel said the other glass panes on the VPAC were not in immediate danger.

“It’s not unheard of in a design like this where the entire wall of the building is made of these glass assemblies,” he said. “It’s not unheard of, but I wouldn’t say the thing is at risk.”