"The bombardment of Bustan al-Basha has stopped but could start up again anytime," a resident said.
The shelling destroyed houses in the northern city's Midan district, a regime bastion that rebels have been trying to seize from their stronghold in Bustan al-Basha since Saturday, said the Syrian Observatory for Human Rights.
A main water pipe in Bustan al-Basha was destroyed on Saturday, either by air strikes or the fighting, and residents reported water shortages in the northern city.
The water department said the pipeline was still broken on Sunday, but repairs were underway.
Aleppo province governor Mohammed Akkad blamed "terrorists" for breaking the Midan watermain as well as two other pipelines in Suleiman al-Halabi district.
"Maintenance crews are in the process of repairing them and we hope that the water will return on Sunday," he told pro-regime daily Al-Watan.
The Observatory reported an unknown number of casualties in Hanano after heavy shelling hit a building in the eastern neighbourhood.
On Saturday, troops backed by tanks and helicopters had repelled a rebel attack on the Hanano military base after a 20-hour battle.
Al-Watan newspaper declared on Sunday that "the Hanano barracks are in the hands of the army".
The government forces had pushed rebels out of the fortress-like compound on Saturday, parts of which rebels claimed to have captured the day before, military officials and witnesses said.
In Damascus, troops bombarded Tadamun, in the southeast, and the nearby district of Al-Hajar Al-Aswad as clashes broke out at the Yarmuk Palestinian camp, the Observatory said.
Al-Watan reported the army was "scouring" Tadamun after entering the district on Saturday for "armed men".
Clashes killed three rebels in Harasta, to the northeast of Damascus.
Killed by sniper fire
In the eastern city of Deir Ezzor, the army shelled the neighbourhood of Jubaila, while two people were killed at a checkpoint in Hamdaniyeh district and a third was shot dead by a sniper in Jura.
Shelling attacks were also reported in the northwestern province of Idlib and in the southern province of Daraa, where two men were killed by sniper fire, the Observatory said.
The Homs city suburb of Khaldiyeh saw clashes as well as shelling, while dozens casualties were reported as a bus carrying civilians and soldiers was bombed on a main road in the central province.
At least 12 people, including nine civilians, were killed nationwide on Sunday, the Observatory said.
The violence followed a bloody day in which 135 people – 63 civilians, 33 rebels and 39 soldiers – were killed nationwide, the Britain-based Observatory reported.
As many as 38 people were killed by shelling attacks on the districts of Shaar, Halwani and Sid al-Luz on Saturday, the watchdog said. The names of 17 have been documented thus far.
Another 17 bodies were discovered in a trench in Aleppo city, while at least 11 people were killed in shelling in Tadamun and Yarmuk Palestinian camp in Damascus. – Sapa-AFP