PITTSFIELD — Residents may have noticed the flatbed truck carrying a unique wooden structure driving around the city on Tuesday.

PITTSFIELD — Residents might have noticed the flatbed truck carrying a unique wooden structure driving around the city Tuesday.

It was a traveling stage that, over the past few days, has been ferried to locations in Pittsfield and Lee, from which renowned musicians Yo-Yo Ma and Emanuel Ax played a series of surprise pop-up concerts for essential workers.

“The intention was really to give a gift to the Berkshires community,” said Carrie Holland, the managing director of Mill Town Capital, which co-organized the series with the musicians and Jennifer Glockner, director of the city’s Office of Cultural Development.

The pop-up concerts came on the heels of the performance the Grammy award-winning cellist and pianist gave Sunday for a limited crowd of essential workers at Hancock Shaker Village.

Organizing the surprise concert series entailed a fair amount of secrecy, Holland said. Aside from a designated “point person” at each workplace, the essential workers had no idea they would be treated to performances by two world-class musicians.

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“It was a mix of shock and tears,” Holland said. “You couldn’t quite see the smiles behind the mask, but you could see it in their eyes.”

From Sunday to Tuesday, Yo-Yo Ma and Ax gave surprise performances for UPS employees in Pittsfield; Pittsfield Public Schools bus operators; Williams Elementary School teachers; volunteers at the Roots Rising food-distribution center; High Lawn Farm employees in Lee; firefighters, EMTs and Health Department employees at the Columbus Avenue Fire Department headquarters; and health care providers at Berkshire Medical Center.

Yo-Yo Ma wanted to give back to the employees and volunteers, she said, and wanted to find a way to safely perform live. Organizers placed Hula-Hoops on the ground to enforce social distancing and to ensure that no more than 50 people attended each performance.

The hard-to-miss traveling stage was designed and built by artist Mike Rousseau, along with Mitch and Seth Nash of Blue Q, Holland said.

Amanda Burke can be reached at aburke@berkshireeagle.com, on Twitter @amandaburkec and 413-496-6296.