Factions of the Syrian rebels fighting against President Bashar al-Assad's troops reportedly killed dozens of residents of a town in eastern Syria where pro-regime agents had attempted to enlist and arm fighters.
The UK-based Syrian Observatory for Human Rights said at least 60 people, including fighters loyal to Assad and possibly some civilians, were killed in Hatla Tuesday.
Shia residents of the rebel-held town fled.
The Observatory, a pro-opposition watchdog agency that monitors abuses on all sides of Syria's civil war, reported the incident, which appears to have been a retaliation against villagers who attacked a rebel position.
There is "footage of rebel fighters from several factions storming and burning civilian houses in the Hatla village of Reef Deir Izzor," the group said.
"Rebels also killed several inhabitants (civilians and combatants) of the Hatla village" in what seems to be violence "on a sectarian basis."
More from GlobalPost: Fighting in Syria shifts as sectarian divisions intensify
Some of the rebel fighters have been linked by Reuters to the Al Qaeda-affiliated Jabhat al-Nusra, a Sunni group the United States and other nations have censured as a radical terrorist group.
An online video, titled "The storming and cleansing of Hatla," showed gunmen with black Islamist flags, according to the news wire agency.
A Damascus official told the Associated Press on condition of anonymity that the rebels had "carried out a massacre against villagers in which older people and children were killed."
Syria's war, which began with peaceful protests against the Assad family's rule, has turned increasingly sectarian and savage, with rebels of the mostly Sunni majority fighting Assad's ruling Alawite community, an offshoot of Shia Islam.
About 94,000 people have died since fighting began more than two years ago, according to figures from the Observatory, although the United Nations estimates a more conservative 80,000.
More from GlobalPost: Operation Northern Storm: Syrian army plans assault on Aleppo
Last week, fighters from Lebanon's Shia militant group Hezbollah aided Assad's troops in recapturing the strategic western town of Quasyr. Now, Assad's forces are poised to attack the northern city of Aleppo.
On Wednesday, France called on the international community to stop the Hezbollah-backed government forces from reaching the city. "We must stop this progression before Aleppo. It is the next target of Hezbollah and of the Iranians," Foreign Minister Laurent Fabius said.
"We need to re-balance things because over the past few weeks the troops of Bashar al-Assad and especially Hezbollah and the Iranians, along with Russian arms, have gained considerable ground," he added.
UK Foreign Secretary William Hague is in Washington on Wednesday for talks with US Secretary of State John Kerry about what the West can and should do — if anything — about Syria's war. One of the options being considered by the White House: arming the rebels.
More from GlobalPost: Syria: One on one with the leader of Jabhat al-Nusra