Clashes Erupt Over Missing Mexican Students MEXICO CITY - A day of mostly peaceful antigovernment mass marches on Thursday to protest the disappearance, and presumed murders, of 43 college students ended with clashes with the police who tried to prevent some demonstrators from damaging the National Palace in the city center. Thousands of people led by relatives of the missing students marched through the city and converged at night at the historic square known as the Zócalo, many of them pleading with masked young people to refrain from violence or stay out of the march. Demonstrators, mostly students and members of teachers" unions joined by celebrities, artists and others, focused their ire on President Enrique Peña Nieto, with echoing shouts of "Peña Nieto out!" and an effigy of the president that was burned. It was one of the largest of the occasionally violent demonstrations that have taken shape since the students, from a left-leaning college with a history of provocative protest, disappeared on Sept. 26 in the town of Iguala, 120 miles south of Mexico City, shocking a country increasingly frustrated with crime and corruption. The authorities have said the mayor of Iguala, who had links to organized crime, ordered his police force to detain the students, fearing they would disrupt a speech his wife planned, with the officers then turning them over to drug gang members who killed them and burned their bodies. Tests are being done on the ashes to confirm whether they are the students" remains. The protesters demanded a full investigation of the disappearance of the students and their return alive, as well as Mr. Peña Nieto's resignation, blaming him for corruption and the lack of progress in the inquiry. Mr. Peña Nieto has promised a thorough investigation and has expressed solidarity with the parents while condemning agitators who took advantage of the demonstrations to vandalize government and political buildings. Two weeks ago, protesters who were believed to be tied to anarchist groups set fire to the door of the National Palace, the symbolic heart of government, lightly damaging it. It seemed the police Thursday night were trying to avoid a repeat of that and ended up in prolonged clashes with demonstrators as they cleared the plaza.