Security forces in Rio de Janeiro used a Catholic church in the city to shoot rubber bullets and fire tear gas at demonstrators.
According to the BBC the Catholic diocese of Rio de Janeiro has called the police's use of one of their churches to fire on protesters an "invasion" and have promised a full investigation into the matter.
Activists were throwing homemade grenades and rockets towards Rio's state government building in clashes which lasted around five hours.
Eleven police officers were injured in the clashes, according to a statement from military police. There also were reports of protesters being injured.
The protests are over a mixture of government cost-cutting plans and various corruption scandals among politicians.
The recent financial crisis in Brazil has seen thousands of state employees and retirees not getting paid or being paid months late.
The mayor of Rio Sergio Cabral and his wife have been charged with alleged corruption, along with other Brazilian politicians.
The clashes cast a sad shadow on the recent Rio 2016 Summer Olympics, widely hailed to be a success for the city and the nation.