Hundreds of masked youths battled police and set 30 cars ablaze Monday as police in Paris blocked the route of more than 100,000 students demanding better conditions at their high schools. It was the worst violence in a month of nationwide student protests. Riot police fired water cannons and hundreds of rounds of tear gas at demonstrators, who pelted officers with rocks and bottles, smashed windows and looted stores. Police headquarters said 104 officers were hurt, including 18 hospitalized. Police reported 52 arrests in Paris, and a dozen youths arrested for vandalism during a protest march in Montbelaird, eastern France. In all, about 100 vehicles were damaged in Paris, police said. About 150,000 students took part in demonstrations elsewhere in France. President Francois Mitterrand promised steps would be taken to address student demands. They want more government spending to improve security, upgrade substandard facilities, modernize curricula and hire more teachers. The main throng of protesters in Paris was orderly, but hundreds of youths on the fringes ran wild. Many rioters wore masks and carried clubs. Journalists were beaten. Mitterrand and Education Minister Lionel Jospin met with a delegation of student leaders and promised an emergency plan in response to demands for better education and safety on campus. Monday's march began at the Place de la Bastille in eastern Paris, where 201 years ago rioters stormed the prison to start the French Revolution. In the Montparnasse neighborhood of southern Paris, gangs started smashing windows and robbing street vendors about two hours after the march started. Police Chief Pierre Verbrugghe, who deployed 5,000 officers, told students they would not be allowed to follow their planned route and finish their march on the Champs Elysees. Many students obeyed the orders, but a few hundred youths squared off against police at the Alma bridge. Police fired water cannons when they tried to cross, scattering the rioters who hurled rocks and trash. The youths regrouped and repeated attempts to break through police line. Vandals set fire to trash and dismantled bus stops. Jospin promised more discussions with student leaders Tuesday and throughout the week, and said such talks should be held on the local level as well. Organizers claimed 200,000 students joined the Paris march, but other observers estimated the turnout at closer to 100,000. It was the first time students from the provinces were urged to join a march in the capital. Those who couldn't come to Paris staged their own protests in dozens of smaller cities. Dozens of previous student marches and rallies across France over the past four weeks have been peaceful, except for sporadic vandalism blamed by student leaders on provocateurs. On Nov. 5, an estimated 150,000 students participated in marches nationwide. The protests began with student strikes last month in the tough northern suburbs of Paris after the gang rape of a girl in a school lavatory and assaults on teachers. Protesters have complained of drug trafficking, theft and extortion on campus. Most protesters come from relatively low-income families, and many are children of immigrants. They view education as the key to advancement, and resent a seemingly second-class treatment of schools in the high-rise slums that ring many major cities. ``I'm from a bourgeois neighborhood, so our problems with security and infrastructure are not that great,'' said marcher Fabien Liabastre, 16, of Sceaux. ``But even our school has wire hanging out of the wall and water leaks throughout the ceiling.'' The students have broad public support and the government has proposed increasing the education budget by 9 percent in 1991. But students worry that improvements won't come quickly enough to help them win university admission or decent jobs.