A pregnant woman and three children were among 18 civilians killed Tuesday when Syrian fighters shelled a Kurdish-majority neighborhood in the northern city of Aleppo, according to the Britain-based Syrian Observatory for Human Rights (SOHR).
The monitoring group said 70 people, including 30 children, were also wounded in the attack. The attack was mounted by Jabhat al-Nusra and Ahrar al-Sham, and is described as a violation of the ceasefire that was negotiated February 27.
While Nusra is excluded from the ceasefire, Ahrar al-Sham is not.
The shelling targeted Sheikh Maqsud area, where up to 50,000 residents are caught in the crossfire between government strongholds and opposition-held districts.
In a separate incident on Tuesday, fighters belonging to ISIS attacked government-held areas near Damascus. An ISIS statement said the group attacked the Tishrin power station 50 km northeast of the capital, and a Syrian military source confirmed the assault but said all the attackers had been killed. The source added that the attack appeared to be ISIS's response to reverses it suffered around Palmyra.
Syrian and allied forces, backed by Russian air strikes, have forced ISIS out of the town of al-Qaryatain, 100 km west of Palymrya, which was recaptured by the government last week. Russian forces have since been clearing the area of mines.
Also on Tuesday, ISIS used five bomb-laden cars to strike military positions near the airport, southeast of Damascus, killing 12 soldiers, reported SOHR.
Government forces responded with shelling and air strikes in the same area, and jets struck the town of Dumeir, 40 km northeast of Damascus, which is held by a group described as "sympathetic" to ISIS.
The Islamist groups also shot down a Syrian warplane in the Aleppo region on Tuesday and captured the pilot alive. The Syrian regime and its allies launched a large assault in that area overnight on Tuesday, the largest since the implementation of the ceasefire.
Hezbollah's al-Manar news agency said that the offensive is supported "by heavy and concentrated airstrikes."