At least 35 civilians were killed in a rocket attack on a busy market in a government-held district of Syria's capital Damascus, state media report.
Rebels in the besieged Eastern Ghouta region fired the rockets at Kashkoul, police told the Sana news agency on Tuesday.
Six other civilians were injured in a separate attack to the west, they said.
Rebel groups have stepped up artillery attacks since pro-government forces launched a major air and ground assault on the Eastern Ghouta a month ago, according to a BBC report Wednesday.
The intense bombardment of the enclave by the Syrian military and its allies is believed to have left 1,400 civilians dead and led 50,000 others to flee.
Earlier, activists said a suspected Russian air strike had killed 15 children and four women sheltering in an underground school in the rebel-held town of Arbin.
UN aid agencies meanwhile expressed alarm at the "massive displacement" of civilians from the Eastern Ghouta and warned that many were in a very poor state of health, with children suffering malnutrition, scabies, diarrhoea and respiratory infections.