Flash floods were triggered by torrential rain, which began on Monday evening and continued into Tuesday.
Some 246 millimeters (9.6 inches) of rain reportedly fell in just nine hours on Monday night, which is above average for the whole month of April. Rio Mayor Marcelo Crivella said that the city faced a "crisis."
Heavy downpours flooded streets, uprooting trees and sweeping away vehicles. Emergency workers were deployed to rescue residents trapped by the downpour.
Schools throughout the city were shut down and classes were suspended as heavy rains continued to overwhelm the city's infrastructure.
Several neighborhoods in Rio's South Zone, including Ipanema, Copacabana and Leblon, were hit the hardest.