A rocket and mortar barrage struck a government-controlled neighborhood in Syria’s northern city of Aleppo on Sunday, killing 13 civilians and wounding 40, the government and an opposition group said.

State-run news agency SANA said the attack by ‘‘terrorists’’ occurred in the predominantly Kurdish neighborhood of Sheikh Maqsoud, which has been subjected to insurgent shelling for days despite a shaky US and Russian-brokered cease-fire that took effect Feb. 27.

The Syrian Observatory for Human Rights, a Britain-based opposition group that monitors the conflict, said more than 70 rockets and mortar shells were fired at Sheikh Maqsoud and reported nine civilians killed, including four children, and 30 wounded.

The Observatory said the shells were fired by insurgents, including the Al Qaeda branch in Syria known as the Nusra Front. That group and its rival, the Islamic State group, are excluded from the cease-fire.