According to reports, most of the deaths were caused by mudslides as many shantytowns are located on hills.
Eduardo Paes, mayor of the state's capital city Rio de Janeiro, said, "In less than 24 hours, the rainfall in the region reached 288 millimeters, surpassing the previous record of 245 millimeters registered in 1966."
About 3,000 firefighters are working to rescue residents, Paes said.
The death toll is likely to increase in the next few hours, as many people remain missing.
The rain continued throughout on Tuesday, Apr 6 and city and state officials warned that hillsides would become vulnerable to mudslides if it continued much longer.