Members of the Free Syrian Army react as they fire a homemade rocket toward regime forces in Deir al-Zor on Sunday, June 16. Tensions in Syria flared in March 2011 during the onset of the Arab Spring, escalating into an ongoing civil war. View the most compelling images taken since the start of the conflict.
(CNN) -- A Syrian rebel brigade blamed "extremists" for a grisly massacre now gone viral on the Internet, and it vowed to punish the perpetrators.
Hossam al Sarmani, a spokesman for the Free Syrian Army's Daoud Brigade in northern Syria, said rogue revolutionaries carried out the killings in Idlib province.
"This execution did take place, and this is the heinous truth," al Sarmani told CNN on Friday. "We will find them, capture them and hold them in a prison until they can by tried by international law or the new Syrian law, God willing."
The gruesome video surfaced Thursday on the Internet.
In it, an armed group of angry men appear to force a smaller group of frightened unarmed men to the ground. They yell at them and kick them, and open fire with automatic rifles until their bodies go lifeless.
On the run with rebels in Syria
Young Syrian amputee's story
Iran behind drone attacks in Syria?
U.N. High Commissioner speaks on Syria
Before carrying out the execution, the gunmen yell at them: "You dogs of Assad!" The poster of the video said the footage was taped in the city of Saraqeb after rebels overran a government outpost.
The opposition Syrian Observatory for Human Rights said "rebel fighters" rounded up and summarily executed more than eight soldiers." It said the rebels also "physically abused the victims before the massacre, kicking them repeatedly."
But al Sarmani -- whose Daoud Brigade is one unit in 6,000-member coalition in the Idlib countryside called the Sham Falcons -- said the attackers have no connection to the FSA rebels.
He said that rebels did indeed fight government soldiers in a raid at a military outpost. In that fighting, rebels killed soldiers, and six to eight troops surrendered.
He said the rebels advanced to another part of the outpost during clashes and left the surrendered soldiers behind. The "extremists" emerged, apparently from Saraqeb and nearby Trambee.
These rogue gunmen took the opportunity to assault the unarmed prisoners, al Sarmani said.
"At this point, a strange group of about 20 men entered among us. We did not know them, but we recognized they were from Saraqeb and the nearby village of Trambee. They were revolutionaries, too, but they were extremists."
He said the "extremists" fled and government warplanes shelled the area, forcing the rebels to retreat and leave the bodies behind. The Observatory said rebels had killed at least 28 government soldiers in fighting in the city Thursday.
On Friday, Saraqeb fell into rebel hands, after the last government checkpoint had been vanquished, the Observatory said. Holding the city would allow opposition fighters to control the main highway to Aleppo, which runs through the city.
"You can't imagine how saddened we are by this crime," al Sarmani said of the massacre.
"We were happy with liberating this outpost. This is not the behavior of Daoud Brigade, and we will always be saddened and disturbed by this story. But we will not stay with our hands tied behind our back. We will find these men and they will face justice," he said.
Mahmoud Bakur, an activist in Saraqeb, condemned the actions and also said they were conducted by extremists.
"We aim to be better than the authoritarian regime that plants these actions among the rebels," he said.
The gruesome scenes drew condemnation from Amnesty International, which said the video showed "a potential war crime in progress."
Read more: Amnesty report finds Nigeria guilty of rights abuses
Amnesty acknowledged being uncertain who the gunmen are and said no one had claimed responsibility. It is investigating the case and admonished all sides "to refrain from torturing, ill-treating or killing their prisoners."
The United Nations said the video is hard to "verify immediately" and must be "examined carefully." But its human rights watchdog said it looks "like a war crime. Another one."
"The allegations are that these were soldiers who were no longer combatants. Unfortunately this could be the latest in a string of documented summary executions by opposition factions as well as by government forces and groups affiliated with them, such as the Shabiha," a spokesman for the U.N. High Commissioner for Human Rights said.
"We were willing to do anything that brings fairness, equality, and freedom. We will work with UN or anyone else to achieve this goal. Without receiving instruction from anyone we have already begun our own investigation."
Rafif Jouejati, a spokeswoman for the opposition Local Coordination Committees of Syria, said "crimes are crimes" and her group doesn't condone "any crimes against humanity."
"However, if this crime was committed by the armed opposition, we still cannot compare it to the Assad regime's daily and continuous bombardment of civilian areas; rampant detention and torture of activists, humanitarian relief workers, and doctors; and systematic terrorism of all communities across the country."
Government aircraft bombarded Damascus and its Idlib and Homs suburbs Friday, the LCC said.
Homs government officials received a delegation from the International Committee for the Red Cross, which is attempting to negotiate with both warring parties over the safe delivery of aid to the hardest-hit areas of the historic center of town.
Read more: U.S. identifying leaders for role in Syrian opposition
The Red Cross and the U.N. refugee agency have recently reported accomplishing inroads in aid delivery despite the dangers of battle and unexploded ordnance.
"We need to make sure both sides stop shooting before we move around," ICRC spokesman Alexis Heeb said from Geneva, Switzerland.
Government and opposition fighters clashed on the ground in Homs on Friday -- as well as in Damascus, Aleppo, Deir Ezzor and Daraa, according to opposition groups.
Fighting has killed 133 people so far Friday, the LCC said. Forty-two of those deaths occurred in Damascus and its suburbs.
Death tolls reported by Syria's opposition usually mount exponentially in the course of a day. At least 149 died Thursday, 121 on Wednesday and 163 on Tuesday, the LCC said.
CNN cannot independently confirm government or opposition reports out of Syria, as the government has restricted access by journalists.
Read more: Young Syrian amputee makes dangerous journey to find help
CNN's Hamdi Alkhshali, Ben Brumfield and Joe Sterling contributed to this report.
Loading weather data ...
© 2013 Cable News Network. Turner Broadcasting System, Inc. All Rights Reserved.
Syrian rebels leave their position in the northwestern town of Maaret al-Numan on Thursday, June 13. The White House said that 
Forces loyal to Syrian President Bashar al-Assad are seen near Qusayr on Thursday, May 30.
Syrian rebels take position in a house during clashes with regime forces in the old city of Aleppo on May 22.
Syrian army soldiers take control of the village of Western Dumayna north of the rebel-held city of Qusayr on Monday, May 13. Syrian troops captured three villages in Homs province, allowing them to cut supply lines to rebels inside Qusayr town, a military officer told AFP.
Rebel fighters fire at government forces in the northern Syrian city of Aleppo on Sunday, May 12.
Searchers use a flashlight as they look for survivors among the rubble created by what activists say was a missile attack from the Syrian regime, in Raqqa province, Syria, on April 25.
A Kurdish fighter from the "Popular Protection Units" (YPG) takes position inside a building in the majority-Kurdish Sheikh Maqsood area of Aleppo, on Apri. 21.
People walk past destroyed houses in the northern Syrian town of Azaz on Sunday, April 21.
Free Syrian Army fighters take positions prior to an offensive against government forces in the Khan al-Assal area, near Aleppo on Saturday, April 20.
Men inspect damage at a house destroyed in an airstrike in Aleppo on April 15.
Syrian and Kurdish rebel fighters walk in the Sheikh Maqsud district of Aleppo on April 14.
A female rebel monitors the movement of Syrian government forces in Aleppo's Sheikh Maqsud neighborhood on April 11.
A rebel runs to avoid sniper fire from Syrian government forces in Aleppo on Thursday, April 11.
Syrian rebels observe the movement of Syrian government forces around Al-Kendi hospital in Aleppo on Wednesday, April 10.
Rescue teams and security forces check out the scene of a deadly car bomb explosion in Damascus on April 8.
The fighting has taken a toll on buildings in Aleppo's Saladin district, seen here on April 8.
A Syrian rebel runs for cover in Deir ez-Zor on April 2.
A rebel checks for snipers across the street toward the Citadel in Aleppo, Syria, on Saturday, March 30, in this photo taken by iReporter Lee Harper.
A Free Syrian fighter mourns the death of a friend in Aleppo on March 30, in this photo taken by iReporter Lee Harper.
A Syrian opposition fighter runs for cover from Syrian army snipers in Aleppo on Wednesday, March 27.
A Syrian girl covers her face to protect herself from fumes as a street covered with uncollected garbage is fumigated in Aleppo on Sunday, March 24.
A Syrian man and his family drive past damaged buildings in Maarat al-Numan, on Wednesday, March 20.
Syrians carry the body of a Syrian army soldier during a funeral ceremony in Idlib province on Tuesday, March 19.
Syrian rebels take position in Aleppo, the largest city in the country, on March 11.
Syrian men search for their relatives amongst the bodies of civilians executed and dumped in the Quweiq River on March 11.
A Free Syrian Army fighter looks back as smoke rises during fighting between rebel fighters and forces loyal to Syria's President Bashar al-Assad on the outskirts of Aleppo on Saturday, March 2.
Residents read Shaam News newspapers published by the Free Syrian Army in Aleppo on March 2.
A member of the Free Syrian Army reacts to the death of a comrade who was killed in fighting, at Bustan al Qasr cemetery in Aleppo on Friday, March 1.
A rebel fighter throws a home-made grenade at Syrian government forces in Aleppo on February 16.
A member of the Free Syrian Army stands with his weapon as he looks at a rainbow in Aleppo on February 16.
A Syrian woman looks through a bus window in Aleppo on February 14.
Free Syrian Army fighters walk through a dust-filled stairwell in Damascus on February 7.
A Syrian rebel gestures at comrades from inside a broken armored personnel carrier in Al-Yaqubia on February 6.
A rebel fighter throws a hand grenade inside a Syrian Army base in Damascus on February 3.
People stand in the dust of a building destroyed in an airstrike in Aleppo, Syria on February 3.
Free Syrian Army fighters run as they enter a Syrian Army base during heavy fighting in the Arabeen neighborhood of Damascus on February 3.
An unexploded mortar shell fired by the Syrian Army sits lodged in the ground in Damascus on January 25.
Fighters from Fateh al Sham unit of the Free Syrian Army fire on Syrian Army soldiers at a check point in Damascus on January 20.
A Free Syrian Army fighter walks between buildings damaged during Syrian Air Force strikes in Damascus on January 19.
A Syrian rebel fighter tries to locate a government jet fighter in Aleppo on January 18.
Syrian rebels launch a missile near the Abu Baker brigade in Albab on January 16.
A Syrian boy walks near rubbish next to tents at a refugee camp near the northern city of Azaz on the Syria-Turkey border, on January 8.
Syrians look for survivors amid the rubble of a building targeted by a missile in Aleppo on January 7.
A father reacts after hearing of a shelling by forces loyal to Syria's President Bashar al-Assad in Aleppo on January 3.
A patient smokes a cigarette at Dar Al-Ajaza psychiatric hospital in Aleppo on December 18, 2012. The psychiatric ward, housing around 60 patients, has lacked the means to function properly since fighting broke out there in July.
Syrians mourn a fallen rebel fighter at a rebel base in the al-Fardos area of Aleppo on December 8.
Members of Liwa (Brigade) Salahadin, a Kurdish military unit fighting alongside rebel fighters, monitor the area in the besieged district of Karmel al-Jabl in Aleppo on December 6.
A member of Liwa Salahadin aims at a regime fighter in the besieged district of Karmel al-Jabl in Aleppo on December 6.
Two young boys sit underneath a washline in a refugee camp on the border between Syria and Turkey near Azaz on December 5.
The bodies of three children, who were allegedly killed in a mortar shell attack that landed close to a bakery in Aleppo, on December 2, are laid out for identification by family members at a makeshift hospital at an undisclosed location of the city.
Smoke rises in the Hanano and Bustan al-Basha districts in Aleppo on December 1 as fighting continues through the night.
Damaged houses in Aleppo are seen after an airstrike on November 29.
A Syrian rebel mourns the death of a comrade in Maraat al-Numan on November 20.
Syrians protesters stand on Assad's portrait during an anti-regime demonstration in Aleppo on November 16.
A Syrian rebel takes cover during fighting against Syrian government forces in Aleppo on November 15.
Syrian opposition fighter Bazel Araj, 19, sleeps next to his pistol in Aleppo on November 11.
A rebel fighter fires at a Syrian government position in Aleppo on November 6.
A Syrian rebel leaps over debris left in the street while running across a "sniper alley" near the Salahudeen district in Aleppo on November 4.
Rebels hold their position in the midst of a battle on November 3 in Aleppo.
A man cries while being treated in a local hospital in a rebel-controlled area of Aleppo on October 31.
A man is treated for wounds after a government jet attacked the Karm al-Aser neighborhood in eastern Aleppo on October 31.
A Syrian rebel interrogates a handcuffed and blindfolded man suspected of being a pro-regime militiaman in Aleppo on October 26.
Smoke rises from a fuel station following a mortar attack as Syrian women walk on a rainy day in the Arqub neighborhood of Aleppo on October 25.
A Syrian rebel fires at an army position in the Karm al-Jabal district of Aleppo on October 22.
A wounded Syrian boy sits on the back of a truck carrying victims and wounded people to a hospital following an attack by regime forces in Aleppo on October 21.
A man lies on the ground after being shot by a sniper for a second time as he waits to be rescued by members of the Al-Baraa Bin Malek Battalion, part of the Free Syria Army's Al-Fatah brigade, in Aleppo on October 20.
Syrian army soldiers run for cover during clashes with rebel fighters at Karam al-Jabal neighborhood of Aleppo on October 20.
Smoke rises after a Syrian Air Force fighter jet fired missiles at the suburbs of the northern province of Idlib on October 16.
A Syrian opposition fighter stands near a post in Aleppo on October 11.
A Syrian man mourns the death of his father, who was killed during a government attack in Aleppo on October 10.
A rebel fighter is carried by his friends and laid on a gurney to be treated for gunshot wounds sustained during heavy battles with government forces in Aleppo on October 1.
Syrian rebels help a wounded comrade to an Aleppo hospital after he was injured in a Syrian army strike on September 18.
Free Syria Army fighters are reflected in a mirror they use to see a Syrian Army post only 50 meters away in Aleppo on September 16.
A Syrian man carrying grocery bags tries to dodge sniper fire as he runs through an alley near a checkpoint manned by the Free Syria Army in Aleppo on September 14.
A woman walks past a destroyed building in Aleppo on September 13.
Free Syrian Army fighters battle during street fighting against Syrian army soldiers in Aleppo on September 8.
A Syrian man wounded by shelling sits on a chair outside a closed shop in Aleppo on September 4.
A woman sits in her wheelchair next to her house, damaged by a Syrian air raid, near Homs on August 26.
Members of the Free Syrian Army clash with Syrian army soliders in Aleppo's Saif al-Dawla district on August 22.
A man mourns in front of a field hospital on August 21 in Aleppo.
Wounded civilians wait in a field hospital after an air strike on August 21 in Aleppo.
People pray during the funeral of a Free Syrian Army fighter, Amar Ali Amero, on August 21.
A man cries near the graves of his two children killed during a recent Syrian airstrike in Azaz on August 20.
A Syrian woman holds her dead baby as she screams upon seeing her husband's body being covered following an airstrike by regime forces on the town of Azaz on August 15.
A Syrian rebel runs in a street of Selehattin during an attack on the municipal building on July 23.
Syrian rebels hunt for snipers after attacking the municipality building in the city center of Selehattin on July 23.
Members of the Free Syrian Army's Mugaweer (commandos) Brigade pay their respects in a cemetery on May 12 in Qusayr.
Syrian rebels take position near Qusayr on May 10.
A Free Syrian Army member takes cover in underground caves in Sarmin on April 9.
Rebels prepare to engage government tanks that advanced into Saraquib on April 9.
Men say prayers during a ceremony in Binnish on April 9.
A young boy plays with a toy gun in Binnish on April 9.
A Free Syrian Army rebel mounts his horse in the Al-Shatouria village near the Turkish border in northwestern Syria on March 16, a year after the uprising began.
Syrian refugees walk across a field before crossing into Turkey on March 14.
A rebel takes position in Al-Qsair on January 27.
A protester in Homs throws a tear gas bomb back towards security forces, on December 27, 2011.
A man stands under a giant Syrian flag outside the Umayyad Mosque in Damascus on December 24, 2011.
A member of the Free Syrian Army looks out over a valley in the village of Ain al-Baida on December 15, 2011.
Members of the Free Syrian Army stand in an valley near the village of Ain al-Baida, close to the Turkish border, on December 15, 2011.
Displaced Syrian refugees walk through an orchard adjacent to Syria's northern border with Turkey on June 14, 2011, near Khirbet al-Jouz.
A Syrian man holds up a portrait of President Bashar al-Assad during a rally to show support for the president in Damascus on April 30, 2011.
Syrians rally to show their support for President Bashar al-Assad in Damascus on April 30, 2011.
A screen grab from YouTube shows thick smoke rising above as Syrian anti-government protesters demonstrate in Moaret Al-Noman on April 29, 2011.
A screen grab from YouTube shows Syrian anti-government protesters run for cover from tear gas fired by security forces in Damascus on April 29, 2011, during the "Day of Rage" demonstrations called by activists to put pressure on al-Assad.
Syrians wave their national flag and hold portraits of al-Assad during a rally to show their support for their leader in Damascus on March 29, 2011.
A woman sits by the hospital bed of a man allegedly injured when an armed group seized rooftops in Latakia on March 27, 2011, and opened fire at passers-by, citizens and security forces personnel according to official sources.
Syrian protesters chant slogans in support of al-Assad during a rally in Damascus on March 25, 2011.
|