CHICAGO (CBS) — Members of the Chicago Symphony Orchestra went on strike after negotiations broke down on Sunday.

According to the Chicago Federation of Musicians, the musicians announced they would not return until an agreement had been reached. The last time a CSO strike took place was in 2012.

“We have been clear from the beginning that we will not accept a contract that diminishes the well-being of members or the imperils the future of the orchestra,” said Steve Lester, bassist and Chair of the Musicians of the CSO negotiating committee.

Lester said that beginning at 8:00 Monday morning, picket lines will form across “all the doors of Orchestra Hall” through 8:00 p.m. every day until a contract is reached.

“The walk out and forming of a 12-hour daily picket line is driven by management’s insistence on reducing retirement benefits. When the Orchestra is performing at the top of its game and having its best year ever at the box office, we’ve got to protect the artistic integrity of one of the world’s great orchestras,” added Lester.

According to the musicians, some of the sticking points include a pay raise and retirement benefits. According to the musicians’ union, the labor contract with the Chicago Federation of Musicians, which expired in September of 2018, was extended to March 10 to “facilitate discussions and to explore the musicians retirement needs.”

In a statement, a CSO board member said they look forward to the eventual resolution to a new contract.

RELATED: From 2012, CSO Musicians Strike Throwing Season Into Chaos