Air strikes on rebel-held neighborhoods in Syria's second city Aleppo on Friday killed at least 14 civilians and wounded more than a dozen others, the local civil defense told AFP.
The Syrian Observatory for Human Rights said regime warplanes carried out the air strikes and gave a toll of 10 dead.
An AFP correspondent in the opposition-held eastern part said several neighborhoods were targeted and that the wail of ambulances could be heard throughout the morning.
In Bustan al-Qasr, one of the most heavily-populated neighborhoods, a strike hit a five-storey apartment building, shearing off part of an entire floor.
Civil defense volunteers were climbing into the building to search for families trapped in the rubble, according to the AFP journalist.
Seven civilians were killed and 10 wounded there, a civil defense member said.
Two other people were killed and eight wounded in Al-Mashad district, the source said, adding that in the opposition-held Salhin neighborhood a strike killed five civilians.
The Britain-based Observatory said the air strikes targeted Bustan al-Qasr and other Aleppo neighborhoods, killing at least 10 people and wounding dozens more.
"The number of martyrs is expected to rise because many of those wounded are in critical condition," said the monitor, which relies on a network of sources inside Syria for its reports.
Once Syria's commercial hub, Aleppo has been divided between rebel control in the east and government forces in the west since 2012.
Nearly all warring parties in Syria – the regime, rebels, jihadists, and Kurds – have carved out zones of control in war-torn Aleppo province.
A ceasefire took effect in Syria at the end of February but the country has been rocked by fighting in recent weeks, particularly around Aleppo.
On Sunday, at least six civilians were killed in government strikes on eastern parts of the city, and another 16 were killed by rocket fire by Islamist rebels.
Syria's conflict erupted in March 2011 with anti-government protests, but has since spiraled into a multi-front war that has left more than 270,000 people dead.
AFP contributed to this report.