CHICAGO (CBS) — Musicians at the Chicago Symphony Orchestra went on strike Saturday, disappointing patrons who showed up for an evening performance, and potentially throwing the organization’s upcoming season into chaos.

CBS 2’s Suzanne Le Mignot reports concertgoers had planned to listen to Dvorak’s 5th Symphony at the CSO Saturday night. Instead, they were met by silence, in the form of musicians holding picket signs outside Symphony Center.

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The musicians’ contract expired last Sunday. Since this summer, the musicians and CSO management had been negotiating for a new contract.

Earlier in the week, rehearsals and concerts took place, but the CSO association said, during negotiations Saturday, the musicians left the negotiating table to go on strike.

The musicians said the key issues for them are salary and healthcare.

The association’s apparently insisting that we take a significant increase in paying for the cost of healthcare … which would mean a net loss in our income,” said Stephen Lester, chairman of the Orchestra Members Committee.

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“They currently make a minimum of $144,000 per year. In the final year of this contract they would have a base minimum wage of over $150,000. I say base minimum because there are overages; so, in fact, in this year – when they make $144,000 – the average salary of a Chicago Symphony Orchestra musician is $173,000,” said CSO Association President Deborah Rutter.

Concertgoers were met with signs on the doors of the Symphony Center on Saturday, announcing the strike, shortly before the 8 p.m. concert. While some were very upset, others took the disappointment in stride.

“I’m upset. I’m a music major, and I was so excited to see the symphony, and now they’re not performing anymore, so we’re all dressed up to go bowling,” said Abby Calhoun.

“It’ upsetting, because their main complaint is economic and healthcare costs, and my healthcare costs are up, your healthcare costs are up. So are everybody else’s,” said Rick Baumgarten. “I mean, just because you’ve got a union, and you can strike, doesn’t mean you should.”

Currently, CSO musicians make $144,820 a year. With overtime and seniority, the average annual pay is $173,000 a year, including 12 weeks paid time off.

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Ticket holders for Saturday night’s performance were told they could get refunds, exchange their tickets for other performances, or donate them. The next scheduled concert is Wednesday. The CSO Association said they hope a resolution is reached by then.