Transmission short circuits in Tocantins led to power outages that affected as many as 6 million electricity customers in Brazil.
Worsening the situation, drought conditions and a corresponding dip in hydropower generation have caused power shortages, according to Brazil's national grid operator, ONS.
Brazilian utilities Light SA, which serves Rio de Janeiro, and AES Electropaulo SA, which delivers power to Sao Paulo, have reported outages along with nine other utilities, according to the government.
Hydropower reservoirs in Brazil are at about 40 percent of their usual capacity. Hydroelectricity feeds about 80 percent of Brazil's electric power demand.