Military police are facing off with protesters in the middle of Sao Paulo's metro system.<br/> <br />An ongoing strike by metro workers has tensions rising -- less than a week before the FIFA World Cup kicks off.<br/> <br />Friday's face-off saw police threaten protesters with guns.<br/> <br />A protester's hand can be seen trying to coax the police into lowering their weapons.<br/> <br />But like the ongoing worker negotiations, this attempt to calm the police proved futile.<br/> <br />The protest ended with tear gas, rubber bullets and stun grenades.<br/> <br />Of 63 stations throughout the city, 31 were closed.
