An amateur video filmed in Syria and apparently showing the mass execution of pro-government forces in Aleppo at the hands of Free Syria Army rebels.
The video — in which several members of the same Aleppo family several members of a prominent Aleppo family, the Barris, who have close ties to the government of President Bashar al-Assad, are killed — could reveal a war crime, human rights activists have reportedly said.
According to The New York Times, the video — posted by anti-government activists on YouTube — shows more than a dozen men with bloodied clothes and faces gathered in the room of a school decorated with a mural depicting Mickey Mouse, SpongeBob SquarePants and other cartoon characters.
They are made to give their names and accused of being pro-government militiamen known as shabiha.
Several are said to be members or associates of the Barri clan, one of them giving his name is Ali Zein El Abidin Barri.
The Barri family, a Sunni clan, is known for suppressing opposition to Assad, the Times wrote. They are accused of killing 15 anti-government fighters after initially pledging to let them pass through an area of Aleppo they controlled.
The footage later shows the men stripped down to their underwear being put up against a wall and shot with Kalashnikov rifles, with the shooting lasting 40 seconds and a cloud of dust clearing to reveal a pile of bodies.
Human Rights Watch told the BBC the act was potentially a war crime.
Clive Baldwin, a senior legal adviser for HRW, said: "What it looks like is execution of detainees and if that is the case, that would be a war crime."
The video depicting the apparent massacre has not been verified, but the UK-based Syrian Observatory for Human Rights said such vengeance was a crime under Islamic law condemned any such killings by the rebels as "criminal."
Assad's forces have been battling to oust Free Syria Army rebels from Aleppo, the country's biggest city and its commercial capital, since last month.
It was not the first report of rebels carrying out executions against pro-Assad forces without trial.
Reuters cited another video shot at a police station in the town of Nayrab, southeast of Aleppo, in which one rebel says: "Come and see the carcasses that die for the sake of Assad.
The camera is taken into the police station to reveal at least 15 bodies inside the building, with a rebel pointing his rifle at the body of the station commander of the station and firing a bullet that blows his head off.
"I spit on you, and on the tyrant Bashar al-Assad," the unidentified fighter reportedly says.
The news service also cited Ahmed, a rebel fighter from the Amr bin al-Aas brigade which operates in the Syrian town of Azaz, as saying that a Syrian army sniper named Rami had been shot dead after a graveside "trial."
Russia Today, meantime, quoted that country's Deputy Minister of Foreign Affairs, Gennady Gatilov, as saying on Twitter: "The brutal massacre of government supporters by the opposition in the city of Aleppo shows that human rights violations are being committed by both sides."
More from GlobalPost: Syria: How it all began with a couple of kids and a can of spray paint