Some workers at Sao Paulo's metro started an indefinite strike on Thursday, disrupting three of the city's five subway lines and stranding millions of commuters a week before the soccer World Cup kicks off.
Train, bus and police strikes have been common in Brazil as workers use the high-profile event as an excuse to push for higher salaries and benefits, walking off the job regardless of whether courts grant the strikes legal status.
On Thursday frustrated passengers broke the doors to a stalled train and walked onto the tracks at the Itaquera stop when their commutes were interrupted. The station, which will transport thousands of soccer fans to the Corinthians arena for the World Cup's opening match on June 12, was operating normally by mid morning.
Local television showed workers in eastern Sao Paulo, a poorer area of South America's largest city, returning home after they had no way to get to work. More than 4 million commuters were left without transportation.
Traffic was more congested than usual in Brazil's business hub although less severe than it was a week ago when a two-day bus strike caught the city by surprise.
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Many soccer fans are expected to rely on limited public transportation to get to stadiums on game days at 12 host cities during the month-long tournament.
New public transport projects promised for the World Cup have not been started and many are unfinished, leading to widespread anger over the cost of building or renovating stadiums that have become symbols of waste.
The broken promises contributed to waves of street protests last year and have hurt the popularity of President Dilma Rousseff ahead of elections in October. On Wednesday night, some 10,000 people joined the homeless workers movement in a peaceful march to protest for housing near Sao Paulo's World Cup stadium.
Sao Paulo will host the opening match between Brazil and Croatia on June 12 at the Corinthians arena, which has been criticized for driving up property values and pricing long-time residents out of a working-class neighborhood.
Salary negotiations for the striking metro workers were expected to resume later on Thursday.