By SARA BURNETTCHICAGO (AP) â¿¿ Hundreds of teachers, parents and other opponents marched through downtown Wednesday, vowing to fight a plan to close 54 Chicago Public Schools, despite Mayor Rahm Emanuel's comments that he's done negotiating and the closings are essentially a done deal. Emanuel and schools chief Barbara Byrd-Bennett say the nation's third-largest district must close dozens of schools because CPS faces a $1 billion budget shortfall and has too many schools that are half-empty and failing academically. At a rally before the march, Chicago Teachers Union President Karen Lewis called the closings "injustices" and said lawsuits are planned. Other speakers called for state and federal lawmakers to intervene. "There are many ways that you can show that this is not over," Lewis told the protesters, whose march filled the street and stretched a full city block. "On the first day of school you show up at your real school. Don't let these people take your school." Stopping in front of City Hall, the protesters chanted "Save our Schools" and called for Emanuel's ouster. More than 100 people who had planned to be arrested sat down in the middle of the street, where they continued chanting until police cleared them from the area and issued citations. Retired teacher Gloria Warner, 62, was among those sitting arm-in-arm with other protesters in the roadway, which was blocked off to rush hour traffic. "We need the mayor and CPS to invest in our schools, not take them away," the grandmother of two CPS students said. "We need our schools for the safety of our children." A group of Chicago ministers also went to City Hall on Wednesday to deliver a letter asking Emanuel to halt the plan. CPS and the mayor say the closings will save the district $560 million over 10 years in capital costs and an additional $43 million per year in operating costs. About 30,000 students â¿¿ almost all of them in Kindergarten to eighth grade â¿¿ would be affected.