More than 40 people have been killed and around a hundred injured by Al Nusra militants shelling in the Syrian city of Aleppo, Russian news agencies cited the Russian ceasefire monitoring center in Syria as saying on Saturday."There was continuous bombardment by rocket launchers, canon artillery, mortars and anti-aircraft installations. The terrorists shelled several areas of the city inhabited not only by government forces and Kurdish troops but also civilians," TASS news agency quoted a monitoring center official as saying.