From top to bottom, rescuers scour buildings in Porto Alegre for inhabitants stuck in apartments or on rooftops as unprecedented flooding turned the streets of the Brazilian metropolis into rivers. According to the mayor's office, the level of the Guaiba River that runs past Porto Alegre reached 5.3 meters (about 17.4 feet) on Sunday -- higher than the previous record of 4.76 meters recorded during historic floods in 1941. Read this story