Guest conductor Yutaka Sado led the orchestra during a performance that attracted a special guest. (Stephen Elliot)

A baby mouse tested the limits of concert convention Thursday night when it raced up and down the aisle in the Kennedy Center’s Concert Hall, eliciting a few squeals and much commotion in a setting known for its strict silence and decorum.

The critter showed up at intermission of the concert featuring conductor Yutaka Sado leading a program that is part of the year-long Leonard Bernstein celebration.

Attendants were called to the lower orchestra section, and they asked ticket holders to stay in their seats as the second half of the program — featuring Tchaikovsky’s “Francesca da Rimini” — got underway. The music continued without interruption.

There have been other mouse sightings at the Kennedy Center in recent months, but on Thursday the baby didn’t quickly disappear. It instead scurried around 12 or more rows near the left aisle, forcing audience members to move their coats and bags as they struggled to remain quiet and still.

That dark speck is the mouse that scurried around the Kennedy Center’s Concert Hall on Thursday night, distracting audience members but not the orchestra. (Savannah Stephens/The Washington Post)

There were several gasps and squeals and lots of neck craning, and at least one man left, although it’s only speculation that the mouse figured in his decision. Those in the front rows bolted as soon as the final notes were played.

A spokeswoman for the NSO said the Kennedy Center is an old building and that it is treated regularly for pests. The recent cold snap could have played a role, she said, in the mouse’s appearance. There were no requests for refunds afterward.

The concert repeats Saturday night.

This post has been updated.