Just before 8 on a Friday night, when Orchestra Hall would normally be buzzing, the lobby was quiet. The doors were locked, the lights low, the escalator still. No ushers, no bartenders, no ticket-holders.

But onstage, musicians readied themselves for a concert.

String players fiddled with their bows and double-checked their scores. They wore black slacks and shiny black shoes. Bow ties that no audience would see.

At 8:05 p.m., the lights went down and the musicians grew quiet.

As guest conductor Juanjo Mena stepped onstage, followed by piano soloist Kirill Gerstein, the players cheered and stomped their feet. Mena motioned to Gerstein, and he began playing Rachmaninoff’s Concerto No. 2, its bell-like chords resounding in the empty hall.

But across Minnesota and beyond, people were listening.

“Welcome to Orchestra Hall for a live, history-in-the-making broadcast with the Minnesota Orchestra,” host Melissa Ousley began Classical Minnesota Public Radio’s live broadcast of the March 13 concert, which also included Dmitri Shostakovich’s Symphony No. 7, known as the Leningrad Symphony. A recording of that concert is now available online.

Earlier that week, as officials warned against crowds of 1,000, then 500, then 250, the Minnesota Orchestra, like so many arts organizations statewide, made the call to cancel or postpone weeks of performances. Still, they toyed with the idea of playing for radio, for the last time for who knows how long.

“We had been working in close quarters all week, anyway,” said Andrew Chappell, bass trombone, before the concert began. “It seemed like a reasonable thing to do and a meaningful thing to do for the community.”

The orchestra rehearses and records in the empty hall. But performing a concert without an audience is a little eerie, Chappell said. “We’re going to miss them ... but that’s why we’re doing this, right?”

The room, which seats 2,000, wasn’t completely bare. A dozen staffers spread out in rows and balconies.

Among them was CEO Michelle Miller Burns, who arrived in a puffy parka and a backpack, her face tight. A musician bounded up to her, giving her a forearm bump and making her laugh. This tiny audience had been instructed to clap loudly for the sake of the larger audience listening. The musicians, too, were told to applaud.

During the concerto’s second movement, up in the recording booth, Ousley was receiving a flurry of e-mails from colleagues and listeners, thanking her for the special broadcast. On Twitter, listeners checked in from Minneapolis and St. Paul, Boulder, Colo., and Boston.

“It’s a powerful thing we can do when people can’t go anywhere,” she said. “There are so many things people can’t do right now. We can do this.”

Of course, the hollow hall made her a little nervous. A live broadcast depends on “the enthusiasm and sound of the audience,” Ousley said. A big finish deserves a big round of applause. But she was impressed by the musicians’ cheering at the concert’s start.

“They made more noise than I expected,” said Craig Thorson, the MPR engineer at the board. “You know, those polite musicians.”

It was strange, he noted, not to hear people rustle and cough. Between the concerto’s first and second movements, there wasn’t a single errant clap.

Listeners couldn’t see Mena as he coaxed Gerstein with a slow extension of his wrist. But they could hear his playing deepen. They couldn’t see Gerstein throw his right hand back as he finished the concerto, popping up off the bench. But they could hear the players holler.

Flutist Adam Kuenzel, in the audience, pumped his fists in the air.

Then came Shostakovich’s longest and most famous symphony, which he wrote during World War II as the Germans shelled Leningrad. It requires eight horns, six trumpets, six trombones and tuba. Half the brass section played from the balcony. Through three movements over 70 minutes, the musicians journeyed from lightness to darkness, from sorrow to hope. The players felt the parallels. The symphony, Kuenzel said later, “expresses the anguish that the world is just beginning to feel from this pandemic.”

The symphony ends, at the last second, in C major, in triumph.

“Landing in the key of C major, that was the Leningrad Symphony No. 7 by Dmitri Shostakovich,” Ousley told her listeners, “played tonight by the Minnesota Orchestra, with about 12 people in the audience.”

They couldn’t see it to know for sure, but they could hear her smiling.