Vehicles on fire at the site of a car bomb, said to be in the town of al-Dana, in Syria’s rebel-held Idlib province.

:: A suicide bomber rammed a car laden with explosives into a gathering of rebels near the rebel-held northwestern Syrian city of Idlib on Wednesday, killing and injuring scores, rebel sources said.

They said the blast ripped a textile factory where members of Hayat Tahrir al-Sham, an alliance of rebel groups whose backbone is the former al-Qaeda affiliate Nusra Front, had been using as their quarters. At least 12 were killed, one rebel source said.

The militant alliance has been waging in the last few days a major sweep to round up ultra-hard-line ISIS sleeper cells in Idlib province. They say they have arrested at least 100 people, including who the group says are senior operatives blamed for a string of recent assassination and blasts in the province.

Idlib province is dominated mainly by militant groups although there is some presence of the moderate Western-vetted Free Syrian Army groups.

The province, which borders Turkey, has long witnessed infighting between the main militant groups vying for power.

Although opposed to Syrian President Bashar al Assad’s rule, insurgents are riven by deep divisions on ideology and rivalry that erupts occasionally in deadly clashes.