Nationwide strikes led by Brazilian unions to protest President Michel Temer's austerity measures hobbled public transport in several major cities and closed schools, car factories, banks and other businesses across the country.
Police clashed with demonstrators in several cities, firing tear gas in efforts to clear roadways blocked by burning barricades. Protesters also obstructed the entrances of airports and metro stations.
Mr Temer's efforts to push through pension reforms have deeply angered many Brazilians. The proposed legislation would for the first time set a minimum age for retirement, compelling many employees to work more years to receive a pension and reduce payouts in a country were many workers retire with full benefits in their 50s.
Also stirring unrest is a bill approved by the lower house of Congress this week to weaken labour laws by relaxing restrictions on outsourcing and temporary contracts.
But the government argues economic reforms are needed to pull Brazil out of its worst recession on record, chop the swelling budget deficit, reduce record unemployment and modernise the economy.
The strike had a large impact on auto production in Sao Paulo, which concentrates the bulk of the industry in Brazil.
General Motors, Ford, Toyota and Mercedes-Benz parent Daimler AG all halted production, according to company officials, unions and market analysts. Fiat Chrysler, the No.1 car seller in the country, said it was operating normally.
Union officials said most workers at state-run oil producer Petrobras joined the strike, but the company said the stoppage had no significant impact on output.
"It is important for us to send a message to the government that the country is paying attention to what they are doing, taking away workers' rights," said Marco Clemente, head of the 4000-strong radio and TV workers union in the capital city, Brasilia, as he led a picket line outside the headquarters of state broadcaster EBC.
The 24-hour strike started after midnight on Friday, ahead of a long weekend with Labor Day on Monday.