(CNN) US-backed Syrian Democratic Forces say a prominent politician, her driver, members of Kurdish security forces and several civilians were killed by Turkish-backed militants in Syria on Saturday, after videos circulating online appeared to show the killings.

The Turkish -backed Free Syrian Army or FSA (also called the Syrian National Army), have denied those claims. CNN cannot independently verify the videos.

A video circulating on social media purports to show the bullet-riddled SUV of Secretary-General of the pro-Kurdish Future Syria Party, Hevrin Khalaf, surrounded by several men wearing what appears to be military fatigues.

In a separate video, a body of a woman -- believed to be Khalaf -- is seen lying in rubble with her face and hair covered in dust. At least one man can be seen standing over her and filming. He taps the body with his feet and says, "this is the corpse of pigs." The video is filmed up close and little else can be seen in the clip.

Local journalist Ousama Muhammed, who knows Khalaf, told CNN that the vehicle belongs to her. Meanwhile, the Syrian Democratic Council -- the political wing of the SDF (who led the charge in defeating ISIS in Syria) -- blamed Turkish-backed militias in a statement on Khalaf's death.

"She was taken out of her car during a Turkish-backed attack and executed by Turkish-backed mercenary factions on the International Road between Qamishlo and Manbij, with her driver who was also martyred," the statement said.

Turkish media reports that Khalaf had been killed by aerial bombardment. CNN cannot independently verify how or where Khalaf died.

Photos: The conflict in northern Syria A car burns following a car bomb explosion in Tal Abyad, a city in northern Syria near the Turkey border, on Saturday, November 23. Hide Caption 1 of 41 Photos: The conflict in northern Syria Kurdish demonstrators hurl rocks at a Turkish military vehicle on Friday, November 8, during a joint Turkish-Russian patrol near the town of Al-Muabbadah in the northeastern part of Hassakah on the Syrian border with Turkey. Hide Caption 2 of 41 Photos: The conflict in northern Syria A man stands next to a burning motorcycle at the site of a deadly car bomb explosion in Tal Abyad, Syria, on Saturday, November 2. Turkey's defense ministry blamed the Kurdish People's Protection Units and the Kurdistan Workers Party, while a group aligned with the Kurds blamed Turkey. Hide Caption 3 of 41 Photos: The conflict in northern Syria A man inspects the site of the car bomb explosion in Tal Abyad. Hide Caption 4 of 41 Photos: The conflict in northern Syria A Turkish and Russian patrol is seen near the town of Darbasiyah, Syria, on Friday, November 1. Turkey and Russia launched patrols in northeastern Syria under a deal that halted the Turkish offensive against Syrian Kurdish fighters. Hide Caption 5 of 41 Photos: The conflict in northern Syria Turkish soldiers east of Ras al-Ain watch as a tank fires on positions held by the Syrian Democratic Forces on Monday, October 28. Hide Caption 6 of 41 Photos: The conflict in northern Syria Syrian Kurds wave flags in Qamishli as they take part in a demonstration in support of the Syrian Democratic Forces on October 28. Hide Caption 7 of 41 Photos: The conflict in northern Syria Kurdish forces withdraw from an area near the Turkish border with Syria on Sunday, October 27. Hide Caption 8 of 41 Photos: The conflict in northern Syria Displaced Syrian children sit on classroom tables at a school turned into a shelter on Thursday, October 24. Hide Caption 9 of 41 Photos: The conflict in northern Syria Russian military police began patrols on part of the Syrian border on Wednesday, October 23. Hide Caption 10 of 41 Photos: The conflict in northern Syria People angry over the US withdrawal hurl potatoes at American military vehicles as they pass through Qamishli on Monday, October 21. The image was taken from video provided by the Kurdish Hawar News Agency. Hide Caption 11 of 41 Photos: The conflict in northern Syria US military vehicles drive after pulling out of their base in the northern Syrian town of Tal Tamr on Sunday, October 20. Hide Caption 12 of 41 Photos: The conflict in northern Syria A US service member looks out of an armored vehicle as troops pull out of their base in Tal Tamr. Hide Caption 13 of 41 Photos: The conflict in northern Syria Smoke billows from a fire in Ras al-Ain, Syria, on Friday, October 18. US Vice President Mike Pence announced a day earlier that he and Turkish President Recep Tayyip Erdogan had agreed to a ceasefire halting Turkey's incursion into northern Syria. The Turkish government insisted that the agreement was not a ceasefire, but only a "pause" on operations in the region. Hide Caption 14 of 41 Photos: The conflict in northern Syria A woman reacts as a man's dead body arrives at a hospital in Ras al-Ain on October 18. Hide Caption 15 of 41 Photos: The conflict in northern Syria Displaced Syrians carry their belongings at a refugee camp north of Mosul, Iraq, on Thursday, October 17. Hide Caption 16 of 41 Photos: The conflict in northern Syria Local residents cheer as Turkish army tanks are transported on the outskirts of Akcakale, Turkey, on October 17. Hide Caption 17 of 41 Photos: The conflict in northern Syria A local resident of Ras al-Ain kisses the forehead of a member of the Turkish-backed Free Syrian Army on October 17. Hide Caption 18 of 41 Photos: The conflict in northern Syria Displaced people ride a motorcycle on the outskirts of Tal Tamr, Syria, on Wednesday, October 16. Hide Caption 19 of 41 Photos: The conflict in northern Syria People in Qamishli, Syria, attend a funeral Monday, October 14, for five fighters of the Syrian Democratic Forces. Hide Caption 20 of 41 Photos: The conflict in northern Syria A person inspects damage to a building in Akcakale, Turkey, on Sunday, October 13. The building was damaged by a mortar fired from inside Syria. Hide Caption 21 of 41 Photos: The conflict in northern Syria Some fighters of the Syrian Democratic Forces are buried in Qamishli on Saturday, October 12. Hide Caption 22 of 41 Photos: The conflict in northern Syria Smoke billows from Tal Abyad, Syria, on Friday, October 11. Hide Caption 23 of 41 Photos: The conflict in northern Syria Pro-Turkish Syrian fighters drive an armored personnel carrier across the border into Syria on October 11. Hide Caption 24 of 41 Photos: The conflict in northern Syria People drive past shops in Akcakale, Turkey, that were closed by owners who feared incoming shelling from Syria. Hide Caption 25 of 41 Photos: The conflict in northern Syria Turkish-backed fighters of the Free Syrian Army head toward Tal Abyad, Syria, on Thursday, October 10. Hide Caption 26 of 41 Photos: The conflict in northern Syria Refugees arrive in Tal Tamr, Syria, after fleeing the fighting on October 10. Hide Caption 27 of 41 Photos: The conflict in northern Syria A woman holds a baby after arriving in Tal Tamr. Hide Caption 28 of 41 Photos: The conflict in northern Syria Smoke rises from Tal Abyad, Syria, on October 10. Hide Caption 29 of 41 Photos: The conflict in northern Syria People in Akcakale, Turkey, watch smoke billow from inside Syria. Hide Caption 30 of 41 Photos: The conflict in northern Syria Turkish soldiers move into Tal Abyad. Hide Caption 31 of 41 Photos: The conflict in northern Syria Smoke rises from the Syrian city of Ras al-Ain on Wednesday, October 9. Hide Caption 32 of 41 Photos: The conflict in northern Syria Civilians flee during the bombardment on October 9. Roads were gridlocked with hundreds of fleeing families. Hide Caption 33 of 41 Photos: The conflict in northern Syria Turkish troops prepare for the operation on October 9. Hide Caption 34 of 41 Photos: The conflict in northern Syria Refugees leave their homes near the Turkey-Syria border. Hide Caption 35 of 41 Photos: The conflict in northern Syria Turkish military vehicles drive through Akcakale, Turkey, near the border. Hide Caption 36 of 41 Photos: The conflict in northern Syria Turkey launched airstrikes and artillery fire across the border on October 9. Hide Caption 37 of 41 Photos: The conflict in northern Syria Residents of Akcakale cheer as a convoy of Turkish military vehicles is driven to the Syrian border just after the offensive began. Hide Caption 38 of 41 Photos: The conflict in northern Syria "Our aim is to destroy the terror corridor which is trying to be established on our southern border and to bring peace and peace to the region," Turkish President Recep Tayyip Erdogan tweeted as he announced the start of the operation. Hide Caption 39 of 41 Photos: The conflict in northern Syria Smoke is seen in Tal Abyad, Syria, on October 9. Hide Caption 40 of 41 Photos: The conflict in northern Syria Kurdish people in Ras al-Ain, Syria, wave their group's flags as they protest against a military operation on Monday, October 7. Hide Caption 41 of 41

Several other videos posted online appear to show at least one man on a roadside with his hands tied in northern Syria, whose lifeless body is being fired upon as a man cries out in Arabic "film me shooting him with a sniper rifle" and "pigs...prisoners..kill them."

A media activist on the scene told the New York Times that two men who appeared in the former video -- the one who is dead, and another who appears in that clip alive -- were both killed by a faction allied with the Turkish-backed FSA militia in northern Syria on Saturday.

The New York Times says the militant group Ahrar al-Sharqiyah entered Syria from Turkey and took control of this area of the M4 highway where the killings happened.

The Turkish-backed FSA denies that it was involved, saying none of their forces or factions have reached the M4 highway where the killings happened.

"Our forces haven't reached M4 road, we reached only 712. PYD is saying that she was killed on M4 road, it is known that that road is being bombed and shelled with artillery, this is the first thing," said National Army spokesman Major Yousef Hamoud. "Secondly, it might be an internal job due to a disagreement between political parties that belong to SDF."

The FSA said in a separate statement that they emphasize their "obligation to follow third Geneva Convention 1949 about the treatment of war prisoners and their rights" and said if there had been any violation, it would "follow it up, investigate and hold accountability and search for those who are participating and turn them into the martial judiciary system immediately."

Turkish-backed Syrian fighters watch as smoke billows from the Syrian border town of Tal Abyad.

SDF Press Commander Marivan Qamishlo told CNN that as many as 11 people, including Khalaf, were executed in the same area.

"Nine civilians were executed at the M4 location and two members of the 'Asayish' Kurdish internal security forces at a small check point", says Qamishlo.

He added that politician Khalaf was among the civilians killed, but not at the same time.

"Asayish Kurdish security forces members were killed before Hevrin Khalaf arrived to the checkpoint," said the SDF Press Commander.

The UK-based monitoring group, Syrian Observatory for Human Rights (SOHR), also says that Turkey-backed groups killed nine civilians on the same highway, including Khalaf. They do not specify their sources.

It comes days after Turkish President Recep Tayyip Erdogan launched the incursion into Syria to drive Kurdish forces away from the border and to use the area to resettle around 2 million Syrian refugees. The SDF who operate in the area are US allies, and are led by the Kurdish People's Protection Units (YPG), which Turkey considers a terrorist organization.

On Sunday, Erdogan said the offensive would go 30-35 kilometers into Syrian territory. Turkish-led forces had seized control of Ras Al Ain, he told reporters, while Turkish-backed troops had taken control of 109 square kilometers.

"We are not allowing the establishment of a terror state in northern Syria, and we will not in the future," Erdogan said. "We have no interest in other countries land, however those that set eyes on our lands, we cannot close our eyes/overlook, we don't have the luxury of showing mercy."

There have been 652 attacks on civilians by the PKK/YPG-PYD, he said. "490 terrorists have been neutralized thus far. 440 have been killed, 26 wounded, and 24 surrendered."

"Since when a nation has sat down at the table with a terrorist organization?," Erdogan asked in the press conference.