It gets so quiet during the second movement of the Brahms Symphony No. 2, you could almost hear a pin drop.

Or a sneeze. Or a fist hitting a face.

Such was the case Thursday night at Orchestra Hall in a ruckus the Chicago Symphony Orchestra officially described as “an incident” between “two patrons.” But shocked concert-goers and police called it a fist fight in one of the boxes — where the elite typically sit and expect a more refined experience.

Just as the second movement was drawing to a gentle close — with Music Director Riccardo Muti at the podium — a man in his 30s, according to police, started punching a 67-year-old man inside one of the boxes.

“We heard a rather loud thump,” said Steve Robinson, general manager of Chicago’s classical and folk music station 98.7 WFMT, who was at the performance but didn’t see the fight. “It wasn’t so loud that everyone jumped up and ran for the exits.”

Some in the audience thought a patron had suffered some kind of medical emergency. But police said it was a fight stemming from an argument over seats in the box.

“According to the victim, the offender became irate and struck him several times,” police said.

The victim was left with a cut on his forehead, while the other man left before police arrived, authorities said.

The concert never stopped, but Muti shot a glance over his left shoulder toward the box where the punches were thrown. One concert-goer described the look as “dagger eyes.”

RTWT