Russian air strikes targeted six districts, including al Hallok and al Fardos in Aleppo on Thursday and killed 25 civilians and injured another 60, said Syrian Civil Defence.
Mohamed Yehia, an official from Syrian Civil Defence who is stationed in the city, told Anadolu Agency that defence teams are currently conducting search and rescue operations for survivors under the collapsed buildings.
According to the monitoring group Syrian Observatory for Human Rights (SOHR), nearly 1,400 civilians have been killed in Syria by Russian air strikes since September 2015.
Critics have accused the Kremlin of supporting the regime leader Bashar al Assad by targeting opposition forces, allowing the war to progress in Assads favour ever since.
Russian air strikes have increased in the cities of Idlib, Aleppo, Hama, Homs, rural areas in Latakia, Daraa and southern Damascus.
The Syrian Network for Human Rights (SNHR) also reported that there is evidence showing that Russia "has unlawfully used unguided bombs in densely populated areas," such as on residential areas, homes, mosques and busy markets, as well as medical facilities.