A correspondent for the AFP news agency in east Aleppo said streets were empty with residents holed up indoors and shops shuttered.
Ahmad Ramadan, from the opposition Syrian National Coalition, accused Russia and the Syrian regime of forcing civilians to flee through continued bombing raids.
"Aleppo residents are calling the corridors that Russia is talking about 'death corridors'," he told AFP.
The SOHR also said that Syrian government air strikes killed at least eight civilians in two eastern areas of Aleppo, warning the death toll could rise as more were trapped under the rubble.
UN: Leave Aleppo corridors to us