Air strikes on rebel-held neighbourhoods in Syria's second city Aleppo on Friday killed at least 25 people and wounded more than 40, emergency workers told AFP.
The Syrian Observatory for Human Rights, which said regime warplanes carried out the air strikes, earlier gave a toll of 19 dead but said this was likely to rise.
An AFP correspondent in the opposition-held eastern part of the city said several districts were targeted including Bustan al-Qasr, Al-Mashad and Salhin.
Late Friday, two barrel bombs also hit the southern district of Bab al-Nayrab, killing an ambulance driver.
"It was a bloody, black day in Aleppo, with aircraft not leaving the sky," Bibres Mashaal, the head of civil defence in Bab al-Nayrab, said.
"Twenty-five air strikes where launched on the city, as well as barrel bombs," he said, adding they targeted residential neighbourhoods and main roads.
"Today the civil defence was fully mobilised and there were also fires," Mashaal said.
Civil defence workers also reported three people killed by artillery fire in Bustan al-Qasr, one of Aleppo's most heavily populated neighbourhoods.
An air strike there earlier hit a five-storey apartment building, shearing off part of an entire floor.
"We were sleeping at 10:00 am when the strike hit the fourth floor of the building," said resident Ahmad Radi.
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"We ran down and found the bodies all over the ground."
Civil defence volunteers emerged from the building carrying squirming infants blanketed in dust, while others held limp bodies covered in white sheets.
"It's become normal here for people to die every day. No one even mourns anymore," one Bustan al-Qasr resident said.
"The next day, everyone opens their shops and things carry on as if nothing happened. But everyone living here has lost someone."
"A surprising number of wounded showed up at the field hospital, around 20 people," one medic in an opposition-held neighbourhood told AFP.
"It's more than we can handle," he said, adding that field hospitals in other neighbourhoods were also struggling to cope.
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 Islamist rebel rocket fire.
Syria's conflict erupted in March 2011 with anti-government protests, but has since spiralled into a multi-front war that has left more than 270,000 people dead.