The Syrian regime and rebels were Friday engaged in tit-for-tat attacks in Aleppo, ending a brief lull in violence in the embattled northern Syrian city and sparking fears of more intense conflict.
A series of lethal airstrikes by regime warplanes hit two clinics, a vegetable market and a mosque in rebel-held areas in Aleppo, killing at least 11 civilians, activists and medics said.
The latest attack put one clinic in the Aleppo district of al-Marja out of commission, the Syrian Observatory for Human Rights reported.
Activist Mahmoud al-Shami, who is based in Aleppo, said the mosque struck was located in al-Sukari, an opposition-held district where a major children's hospital was bombarded late Wednesday, leaving dozens dead.
All mosques inside the rebel-held areas in Aleppo cancelled the congregational noon prayers on Friday, according to activists, as residents feared attacks.
Meanwhile, at least 13 civilians were killed in shelling attacks by rebels in regime-controlled areas in Aleppo, the Observatory reported.
Russian news agency Tass, citing a Foreign Ministry statement, said the Russian consulate in a government-held area in Aleppo came under mortar fire. No casualties were reported.
Russia is a staunch backer of Syrian President Bashar al-Assad.
The attacks come less than 48 hours after a hospital supported by the aid group Doctors Without Borders (MSF) was destroyed by airstrikes in al-Sukari, provoking global outrage.
An updated MSF statement said the initial death toll of 30 climbed to more than 50 from the bombarded hospital and the surrounding area.
The fatalities included patients and at least five medical staff, MSF added.
"The sky is falling in Aleppo. The city, consistently at the frontlines of this brutal war is now in danger of coming under a full offensive, no corner is being spared," Muskilda Zancada, the group's head of mission in Syria, said in a statement.
MSF stopped giving out the map coordinates of their clinics and hospitals after a series of raids hit their buildings, before a US and Russian-brokered ceasefire went into effect in most of Syria late February.
"If doctors are killed there is no one to care for the patients who are sick and injured. Killing a doctor is the equivalent of killing more civilians," said Matthieu Amiraux, a spokesman for MSF.
Emile Hokayem, a Middle East analyst with the Institute for Security Studies, accused al-Assad's forces of intentionally targeting civilians.
"Assad's indiscriminate tactical targeting is strategic in nature: it depopulates and debilitates, breaks morale and communities," Hokayem said on his Twitter feed.
Violence has simmered in Aleppo in the past eight days, killing at least 226 civilians, according to the Britain-based Observatory.
The dead included 35 children and 20 women, said the Observatory, which relies on a network of activists inside Syria.
The Syrian army announced a cessation of hostilities in Damascus for 24 hours and the northern Latakia countryside for 72 hours, starting at 1 am (2200 GMT Friday). There was no mention of Aleppo.
A Russian military official confirmed the ceasefire in Latakia, TASS said.
The United States has urged Russia to rein in the Syrian government, as fears grow that the national ceasefire could collapse.
UN officials say the February deal remains the best hope to reduce violence in the country, now in its fifth year of civil war.
Efforts to bring the warring parties to the table in Geneva and negotiate a solution have stalled, after the opposition walked out, citing a lack of progress on humanitarian issues and government attacks.
The truce excluded the Islamic State extremist militia and al-Qaeda-linked al-Nusra Front.
An estimated 250,000 people remain in Aleppo, according to MSF. Advances by the government have put the rebel-held east at risk of siege.
Civilians say fleeing is almost impossible due to the violence. Moreover, the border with Turkey remains shut.
Calm has returned to northern Aleppo province, after armed opposition groups, including Islamist factions reportedly backed by Turkey, attacked Kurdish forces, leaving nearly 70 people dead, mostly on the rebel side.