For the first time in 25 years, teachers in the country's third-largest public school system hit the picket line. After a weekend of unsuccessful 11th hour contract negotiations, the Chicago Teachers Union made good on its promise to walk out on more than 400,000 students at 675 schools. The strike followed more than a year of contentious negotiations over salary, health benefits and job security. It also set up a historic confrontation between Mayor Rahm Emanuel and organized labor in the president's home city and could strain relations between Obama's Democrats and unions. Emanuel decried the strike as "the wrong choice" Monday and urged teachers to continue contract negotiations and get kids back in class. Meanwhile, on Monday, frustrated parents found their plans thrown into turmoil by the sudden news of the strike, NBC 5 Chicago reported. "The kids need to be in school," one said. "This is ludicrous." And after a violent Chicago summer, police Supt. Garry McCarthy said he was "emptying our offices" to patrol the thousands of unsupervised kids on the streets.