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 February 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 cease-fire has brought a sharp drop in violence to much of Syria and has largely held despite sporadic violations and mutual accusations of breaches. The US and Russia are now looking to convince the two sides to return to UN-brokered peace negotiations in Geneva next week.
In a telephone conversation today, Russian Foreign Minister Sergey Lavrov and US Secretary of State John Kerry gave "an overall positive assessment of the progress toward securing the cease-fire in Syria, which is being generally observed and already has led to a sharp decrease in the level of violence," the Russian Foreign Ministry said in a statement.
They stressed the need to avoid delaying the start of the Geneva negotiations.