SAO PAULO (AP) — Some of the biggest demonstrations since the end of Brazil's 1964-85 dictatorship broke out across this continent-sized country, with more expected Tuesday, protests uniting multitudes frustrated by poor transportation, health services, education and security despite a heavy tax burden. Mostly peaceful protests in at least eight big cities drew large crowds, and local news media estimated that at least 240,000 people took part in the demonstrations nationwide. However, demonstrations in Rio de Janeiro and Belo Horizonte were marred by violent clashes with police and vandalism, with several dozen people reported injured. The wave of protests began over a hike in bus prices, but it was also fed by images of Sao Paulo police beating demonstrators and firing rubber bullets during a march last week that drew 5,000. In Rio, the violent police crackdown on a small and peaceful crowd Sunday near the Maracana stadium incited many to come out for what local news media described as the city's largest protest in a generation. The vast majority of Rio's protesters were peaceful, but a group attacked the state legislature building, setting a car and other objects ablaze. The newspaper O Globo cited Rio state security officials as saying at least 20 officers and 9 protesters were injured there. More protests were being planned on social media sites for Tuesday in Sao Paulo and Brasilia. Monday's protests came during soccer's Confederations Cup and just one month before a papal visit, a year before the World Cup and three years ahead of the 2016 Olympics in Rio de Janeiro. The unrest is raising security concerns and renewed questions over Brazil's readiness to host the mega-events. A cyber-attack knocked the government's official World Cup site offline, and the Twitter feed for Brazil's Anonymous group posted links to a host of other government websites whose content had been replaced by a screen calling on citizens to come out to the streets. President Dilma Rousseff acknowledged the demonstrations with a brief statement Monday, saying: "Peaceful demonstrations are legitimate and part of democracy. It is natural for young people to demonstrate." Rousseff's popularity rating recently dipped for the first time in her presidency, largely over sluggish growth, increasing inflation and security worries. She faces re-election next year. The United Nations' Office of the High Commissioner for Human Rights called on the Brazilian government to take "all necessary measures to guarantee the right to peaceful assembly and to prevent the disproportionate use of force." In a press conference Tuesday in Geneva, spokesman Rupert Colville urged authorities "to exercise restraint in dealing with spreading social protests in the country," and also called on demonstrators "not to resort to violence in pursuit of their demands." Brazilians have long tolerated pervasive corruption, but about 40 million Brazilians have moved out of poverty and into the middle class over the past decade and they have begun to demand more from government. Many are angry that billions of dollars in public funds are being spent to host the World Cup and Olympics while few improvements are made elsewhere. In Rio, the confrontation between police and a small group of protesters dragged on late into the night despite sporadic rain. As the group moved on the state legislature building, footage broadcast by the Globo television network showed police firing into the air. At least one demonstrator in Rio was injured after being hit in the leg with a live round allegedly fired by a law enforcement official. Local news media reported that a high school student in Maceio was shot in the face after a motorist forced his way through the demonstrators' barricade. Protesters were raining fists down on the car when a shot was fired. The extent of the 16-year-old's injuries were not immediately known. In Sao Paulo, Brazil's economic hub, at least 65,000 protesters gathered Monday at a small, treeless plaza then broke into three directions in a Carnival atmosphere, with drummers beating out samba rhythms as people chanted anti-corruption jingles. They also railed against the action that sparked the first protests last week: a 10-cent hike in bus and subway fares. Thousands of protesters in the capital, Brasilia, peacefully marched on Congress. Dozens scrambled up a ramp to a low-lying roof, clasping hands and raising their arms, the light from below sending their elongated shadows onto the structure. Some congressional windows were broken, but police did not use force. Maria do Carmo Freitas, a 41-year-old public servant, said Tuesday she was excited about the protests even though she hadn't taken part. "I'm loving it. It's been a long time since we Brazilians decided to leave our comfort zone to tell our leaders that we're not happy about the way things are going," said Freitas. "We pay too much in taxes and we get bad services in exchange, bad hospitals, bad public education, public transportation is terrible." A participant in Monday's march in Sao Paulo agreed. "This is a communal cry saying: 'We're not satisfied,'" said Maria Claudia Cardoso, accompanied by her 16-year-old son, Fernando. "We're massacred by the government's taxes, yet when we leave home in the morning to go to work, we don't know if we'll make it home alive because of the violence," she added. "We don't have good schools for our kids. Our hospitals are in awful shape. Corruption is rife. These protests will make history and wake our politicians up to the fact that we're not taking it anymore!" A survey by the Datafolha polling agency suggested a large majority of participants at the Sao Paulo protest had no affiliation with any political party and nearly three-quarters of Monday's participants were taking part in the protests for the first time. Protest leaders repeatedly warned marchers that damaging public or private property would only hurt their cause. Many Brazilians were angry over Sao Paulo's first protests last week after windows were broken and buildings spray-painted. Police, too, changed tactics. In Sao Paulo, commanders said publicly before the protest they would try to avoid violence, but could resort to force if protesters destroyed property. There was barely any perceptible police presence at the start of Monday's demonstration. In Belo Horizonte, police estimated about 20,000 people took part in a peaceful protest before a Confederations Cup match between Tahiti and Nigeria. Earlier in the day, demonstrators erected several barricades of burning tires on a nearby highway, disrupting traffic. Protests also were reported in Curitiba, Vitoria, Fortaleza, Recife, Belem and Salvador. ___ Associated Press writers Jenny Barchfield in Rio de Janeiro, Marco Sibaja in Brasilia and Jill Langlois in Sao Paulo contributed to this report.