AMMAN: Residents of a former Islamic State stronghold in Syria's northern Aleppo province are sheltering indoors on Monday, 24 hours after infighting between Turkish-backed rebels resulted in dozens of casualties.

Three local rebel factions exchanged heavy gunfire on Sunday, killing more than 10 fighters and civilians—including one police officer—and leaving dozens more injured.

Sunday's battles were the second time in less than a month that opposition forces have turned their guns on each other in the city of al-Bab.

In late May, opposition forces clashed in al-Bab over a local power struggle though the casualties were far fewer than on Sunday.

The revolving door of rebel infighting is the latest setback in Ankara-backed efforts to rebuild and govern the northern Aleppo city after Turkish armed forces and the FSA factions they support expelled the Islamic State (IS) in February.

Since then, internal rebel power struggles, crumbling infrastructure and the local government’s inability to provide basic civil services have threatened Turkey’s projection of authority in the northern Syrian city of more than 100,000 residents.

Sellers showcase their produce in al-Bab on May 10. Photo courtesy of Zein Al-Rifai/AFP.

There are two existing narratives as to why fighting broke out in al-Bab, 40km northeast of Aleppo city, on Sunday.

The FSA faction Firqat al-Hamza accused members of a rival group, al-Fawj al-Awal, of “going around al-Bab, cheering for a-Jolani,” the leader of Jabhat Fatah a-Sham (JFS), Al-Qaeda’s former Syria affiliate. When confronted, the masked gunmen of al-Fawj al-Awal allegedly turned their weapons on civilians, which precipitated a city-wide armed conflict.

Al-Fawj al-Awal contends that they have no relationship with the masked gunmen, having “separated from the group several months ago,” the group announced in a statement posted online on Sunday.

The Islamist faction Ahrar a-Sham, northern Aleppo’s largest and arguably most powerful rebel group, sides with the al-Fawj al-Awal version of events. Ahrar claims that Firqat al-Hamza was the initial aggressor, attacking al-Fawj al-Awal due to longstanding differences and ultimately firing on Ahrar as well when the group attempted to intervene.

Inside opposition territory such as al-Bab, it is characteristic for a low-level inter-rebel confrontation—at times fueled by little more than rumor and hearsay—to escalate into a deadly, large-scale conflict due to a system of coalitional alliances. An attack on al-Fawj al-Awal constitutes an attack against their larger ally: Ahrar a-Sham. The two groups have been linked for more than a year, multiple sources tell Syria Direct.

When a major power such as Ahrar a-Sham joins the fray, heavy weaponry quickly replaces individual firearms. Gunfights do not stay that way for long.

“We have numbers and we have strength, and by the will of God we did not and we will not turn our weapons on anyone,” Ahrar a-Sham announced in a statement on Monday. “But let any hand be raised against our people, or one of our members, and it will be cut off.”

On Monday morning, videos from al-Bab showed empty streets as civilians stayed home, fearing a sudden return of the fighting. Dozens had been caught in the crossfire and injured—alongside rebels—the previous day.

“I saw more than 10 fatalities and 15 injuries, and that’s just at this hospital,” Abdullah a-Ragheb, a nurse at the al-Hikma Hospital in al-Bab, told Syria Direct on Monday. “A police officer was even killed by mistake.”

An uneasy calm returned to al-Bab on Monday as local political forces and Turkish representatives are working to mediate the conflict, the head of the al-Bab Local Council, Jamal Othman, told Syria Direct.

“The infighting has stopped,” he added. “The sides are surrendering prisoners. We are working to resolve the dispute, and our Turkish brothers are playing a peaceful role in managing the conflict.”

Not all residents viewed Turkey’s involvement favorably. Since Turkish-backed FSA rebels expelled IS fighters in February, “there has been chaos in the city, and the Turks have said nothing,” one al-Bab resident, Omar, told Syria Direct on Monday.

“As residents of this area, we demand that the Turks help save us from what is going on in the city,” he added.

Tens of thousands of residents have streamed back home to al-Bab since February, finding a city in ruins. Landmines, planted by IS fighters as they fled, dotted the streets. Residents discovered their homes had been flattened under bombs, their personal possessions looted by retreating gunmen.

An estimated “75 percent” of the city was reduced to rubble, one returning resident told Syria Direct in March.