According to local sources, the incident occurred in the area controlled by "Fastaqim Union", an gang which is a part of "Ahrar al-Sham
...a Syria jihadi group made up of Islamists and salafists, not that there's that much difference, formed into a brigade. They make up the main element of the Islamic Front but they don't profess adoration of al-Qaeda and they've been fighting (mainly for survival) against the Islamic State. Their leadership was wiped out at a single blow by a suicide kaboom at a crowded basement meeting in September, 2014...
" islamist coalition. The series of kabooms, which lasted more than 40 minutes, were caused by detonation in an ammo depot belonging to the aforementioned group.
The exact cause of kaboom is unknown so far. However,
we can't all be heroes. Somebody has to sit on the curb and applaud when they go by...
there is an indirect evidence that might indicate involvement of "Hayat Tahrir al-Sham" (HTS, "Al-Qaeda in Syria") jihadist group.
Weapon and ammo storages in this area are used by both "Ahrar al-Sham" and "Jaish al-Islam
...Liwa al-Islam (Brigade of Islam) was established by Zahran Alloush, the son of Saudi-based religious scholar Abdullah Mohammed Alloush, after Syrian authorities released him from prison in mid-2011 where he had been serving time for his Salafist activism. The group claimed responsibility for carrying out the July 2012 Damascus bombing that killed Defense Minister Dawoud Rajiha, Deputy Defense Minister Asef Shawkat, and Assistant Vice President Hassan Turkmani. It was a driving force behind actions in the Damascus region. It cooperated and conducted joint operations with al-Nusra. In Sptember 2013 Saudi Arabia engineered Liwa al-Islam's merger with fifty other more or less Salafist groups as a counterweight to al-Nusra, which the Learned Elders of Islam considered was growing too powereful..." groups. The latter is currently involved in heavy infighting against fellow jihadists from HTS and "Faylaq al-Rahman" in East Ghouta region near Syrian capital of Damascus. Recently, HTS issued a warning to "Jaish al-Islam" commanders threatening to sabotage their facilities in Idlib province as a punishment for infighting in Ghouta.
Since "Jaish al-Islam" has much less influence and presence in Idlib in comparison to East Ghouta, which is their long-time stronghold, such a scenario is quite possible.