Brazil clashes after President Rousseff praises protests
Riot police and protesters clashed in fresh protests on Tuesday in Brazil's largest city, Sao Paulo.
Shops and banks were vandalised by groups of masked activists, who fought other demonstrators trying to stop the violence.
The protests began earlier this month, with demonstrators calling for a 10% hike in bus fares to be revoked.
But they have since grown into a nationwide movement calling for better education, schools and transport.
More than 50,000 people gathered in front of the Sao Paulo Cathedral on Tuesday for a march through the city centre.
Scuffles broke out with police outside the office of Mayor Fernando Haddad.
Police officers sought refuge inside the building. Stones were thrown, windows broken, and students tried to break down the door.
Journalists were attacked and a car set alight, while protesters set fire to a police post in a street in another part of the city, says the BBC's Luis Kawaguti.
Brazilian TV showed images of a small group of people involved in looting at nearby offices and shops.
Demonstrations also took place in the states of Rio de Janeiro and Minas Gerais.
As the protests continue, Brazil is hosting the Confederations Cup, a curtain-raiser event for next year's football World Cup.
Many of the demonstrators have complained of the huge sums spent on construction for the World Cup and the 2016 Olympics, which will be hosted by Rio de Janeiro.
Brazilian footballer Hulk said on Tuesday that watching the protests made him feel like taking part. At least two other players have sent messages of support on social media.
The demonstrations are Brazil's largest since 1992, when people took to the streets to demand the impeachment of President Fernando Collor de Mello.
On Monday night, more than 200,000 people took the streets of Sao Paulo, Rio de Janeiro and at least 10 other Brazilian cities.
Brazilian President Dilma Rousseff said she was proud that so many people were fighting for a better country.
"My government is listening to the voices calling for change," said Ms Rousseff in her first comments since Monday night's demonstrations.
"Brazil has woken up a stronger country this morning," said President Rousseff.
"The size of yesterday's marches is evidence of the strength of our democracy."
"It is good to see so many young people, and adults - the grandson, the father and the grandfather - together holding the Brazilian flag, singing our anthem and fighting for a better country," said Ms Rousseff.
She said her government had lifted "40 million people into the middle class" but more needed to be done to improve access to free health and education.
President Rousseff later travelled to Sao Paulo for meetings with the mayor and her predecessor, former President Luiz Inacio Lula da Silva.
Mayor Haddad has indicated he is open to the idea of reversing the price increase in transport costs if that is possible, says the BBC's Gary Duffy in Sao Paulo.
The mayors of Cuiaba, Recife, Joao Pessoa and other cities have already announced a reduction in bus fares in response to Monday's protests.
The dilemma for the country's political leadership is how to answer so many different concerns among a vast group of people with momentum and social media on their side, our correspondent reports.
'Free Access Movement'
The wave of protests began earlier this month, with marches in Sao Paulo against a hike in the price of bus fares, from 3 reals ($1.40, £0.90) to 3.20.
They have been organised largely by young people through social media. The organisers called the movement Passe Livre (or Free Access).
Violence also broke out during Monday evening's protests in Rio de Janeiro.
The Rio de Janeiro state assembly was attacked, shops were vandalised and a car was set alight.
"The isolated acts of violence, carried out by a minority, should be vigorously condemned," said Ms Rousseff.
Deputy Sports Minister Luis Fernandes took issue with those protesters complaining about the cost of hosting major sporting events, arguing that the World Cup had provided an opportunity for the country to invest in infrastructure.
Two Confederations Cup matches are due to take place in north-eastern Brazil on Wednesday, between Brazil and Mexico in Fortaleza, and Italy and Japan in Recife.