REUTERS/Hosam Katan
A man reacts at a site hit by what activists say was a barrel bomb dropped by forces loyal to Syria's President Bashar al-Assad, in Aleppo's al-Fardous district April 29, 2015.
AI has concluded that civilians in Aleppo are experiencing "unthinkable atrocities" at the hands of the regime of president Bashar al-Assad, and that indiscriminate aerial attacks on the city have accounted for some 3100 civilian deaths since the beginning of 2014.
Read the full report here
"Civilians in opposition-controlled areas of Aleppo have been bombarded in their homes, hospitals, schools, public markets and places of worship in air attacks launched by government forces," AI writes in the report.
The majority of these attacks involve the use of barrel bombs, which are large oil drums, fuel tanks, or gas cylinders packed with fuel, explosives and metal fragments for increased lethal effect. The regime is alleged to be deliberately targeting civilians in the still-contested city, which is split between regime and opposition control.
In a February interview with the BBC, Syrian President Bashar-Al Assad denied the use of barrel bombs by his forces, according to CNN.
The Syrian government is currently fighting the Al Qaeda affiliate Jabhat al-Nusra, ISIS, secular rebel roups, and Kurdish forces in a multi-sided civil war that's killed upwards of 200,000 people since it began four years ago.
AI's report features testimony from 78 current and former residents of Aleppo as well as 29 people working in the city.
"It was around sunset, and we were sitting near the traffic light in the biggest local market when they attacked," Ahmed, a 25-year old resident of the Al-Fardous neighborhood of Aleppo, told AI, describing two barrel bomb attacks on April 20, 2014.
"Immediately after the first attack, there was another strike. The regime wanted to cause the biggest number of deaths, so they used two barrels," Ahmed said. "After the strike I saw so much dust, women crying and screaming for their children. I saw pieces of bodies and cars burning with people inside. Houses were burning too. There was blood everywhere on the ground."
According to witness accounts, between 35 and 37 people were killed during that attack, all civilians.
Here's what a barrel bombing looks like:
Another attack on June 16, 2014 claimed the lives of 77 civilians, including 7 children, at a public market in the Sukkari neighborhood of Aleppo.
Barraj al-Halabi, a member of the Aleppo Media Center, described the scene to AI when he arrived 10 minutes after the attack.
"Bodies were strewn out on the ground," said al-Halabi. "Six cars were burning, and the people inside them were dead. A little girl came up to me and said, 'My family is inside that building, I need my family.' I told her to be patient and that we would bring them to her. Because of the dust, I couldn't see, and I thought she had a house. But when the dust came down, there was no house at all. She had no house and no family."
AI determined that no fighters were killed during the attack and no military presence was in the area.
REUTERS/Hosam Katan A Civil Defence member looks at the sky fearing another airstrike as he searches for survivors at a damaged site after what activists said was a barrel bomb dropped by forces loyal to Syria's President Bashar al-Assad and hit a school and a residential building in Seif al-Dawla neighborhood of Aleppo May 3, 2015.
"The people started calling, 'A barrel, a barrel,' and we ran to hide inside a building near Nur Shuhada mosque ... Inside the barrel, there is a sharp plate that can cut steel, so how about the humans? They are sliced through. I saw more than 50 injured people. I saw a child whose face was completely turned to blood. Another child was holding in one hand his other hand, which had been cut off completely. He was screaming, 'Bring it back to me.'"
Thirteen civilians were killed during the attack, according to AI.
REUTERS/Hosam Katan Residents walk amidst the rubble of a site damaged by what activists said was a barrel bomb dropped by forces loyal to Syria's president Bashar Al-Assad in Aleppo's al-Saliheen district, May 1, 2015. 
Omar Haj Omar, a member of a civil defence team in the area, described the carnage: "The Civil Defence had seen a helicopter in the air earlier in that area, so we knew they might attack," said Omar.
"I arrived 10 minutes later ... The bomb had hit exactly in front of the Carrefour mall. I saw an ambulance burning, full of dead people, and a minibus that had been full of people ... The driver of a motorcycle had been chopped into two pieces. The body parts were everywhere. I can't say how many people were killed because they were in pieces."
REUTERS/Hosam Katan Men and civil defence members carry an injured man on a stretcher after what activists said was a barrel bomb dropped by forces loyal to Syria's President Bashar al-Assad and hit a school and a residential building in Seif al-Dawla neighborhood of Aleppo May 3, 2015. 
AI believes that the Syrian government's actions in Aleppo amount to war crimes and are a direct violation of international law.