[5] The southern Brazilian electric system relies heavily on multiple powerful hydroelectric plants along the Plate River and its tributaries.Because geography constrains transmission line placement in the area, the Brazilian system is designed to handle multiple contingencies without failure,[9] which may have prevented a worse blackout.[10] In the case of the blackout, heavy rains and strong winds caused[3][11] all three phases on a key 750 kV transmission line from Itaipu to São Paulo to short circuit.[10] The power cut, which Brazilian officials said affected 18 of the country's 26 states, brought chaos to cities including São Paulo, Rio de Janeiro, Belo Horizonte, Campo Grande and Vitória.[2] President Luiz Inácio Lula da Silva arranged an emergency commission to enquire into the cause of the blackout.