Police force striking teachers to end three-week park demonstration 14 (UPI) -- Police in Mexico City say they used tear gas and water cannons to clear striking teachers from a main square where Independence Day celebrations are to be held. The teachers had been camped out at the Zocalo for three weeks in protest of education reforms signed into law by President Enrique Pena Nieto, the BBC reported Friday. The square will be used this weekend for festivities marking the country's independence. Most protesters had left by the Friday deadline, but police tore down temporary shelters of those who remained and put out small fires. Some protesters were arrested. The government claims reforms are needed to reduce the influence of teachers unions in hiring that has resulted in poor teachers being promoted over more qualified teachers. The reforms include performance-based testing for teachers.