Syrian army air strikes have reportedly killed at least 70 people and wounded scores more in the northern province of Aleppo.
The attacks struck civilian areas, including a packed market in a town held by the Islamic State group, activists said.
The deaths occurred in two separate incidents when helicopters dropped explosives-filled barrels.
One hit the rebel-held Shaar neighbourhood of Aleppo, killing at least 12 people, most of them from the same family. They included three children and four women, the Britain-based Syrian Observatory for Human Rights said.
The other attack was far deadlier, hitting a busy market known as Souk al-Hal in the town of al-Bab in Aleppo's countryside.
The Observatory said at least 59 people were killed and dozens wounded, calling it the one of the worst massacres perpetrated by President Bashar Assad's army this year.
The Local Coordination Committees reported more than 50 people killed and around 70 wounded in the al-Bab attack. Both groups document violence through a network of activists on the ground in Syria.
Al-Bab is controlled by Islamic State, which also confirmed the attack in a statement posted on Twitter. It said 50 people were killed in a "devastating massacre" committed by Syrian army helicopters.
Aleppo, once Syria's commercial hub, has been divided between government and opposition forces since mid-2012 and fighting there has raged since.
Government planes have dropped explosives-filled barrels on rebel-held neighbourhoods, killing thousands, while Syrian rebels have shelled residential areas in government-held parts of the contested city, killing hundreds.
The Syrian military has suffered a series of embarrassing setbacks in the north recently as insurgents captured the city of Idlib and almost all of the surrounding province.
Islamic State has also pushed into central Syria, seizing the ancient city of Palmyra after government forces fled the area.
More than 220,000 people have been killed in Syria since the start of the uprising against Assad in March 2011.