The blast yesterday evening killed the key rebel group's leader Hassan Abboud, known by the name Abu Abdullah al-Hamawi, along with 27 other top members.
The attack targeted a meeting of around 50 military and religious leaders in the basement of a house at Ram Hamdan, northeast of Idlib city.
Today, in a video posted on YouTube, Ahrar al-Sham announced that Hashem al-Sheikh, known as Abu Jaber, would replace Abboud as head of the group, with Abu Saleh Tahhan as military chief.
Ahrar al-Sham is a key component in the Islamic Front rebel coalition, which has been battling both President Bashar al-Assad's regime, and jihadists from the Islamic State group.
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No group has claimed the attack on Ahrar al-Sham's leadership and the rebel brigade has not officially pointed the finger at any organisation.
All of Idlib province, with the exception of its capital, is under the control of various rebel groups after IS militants were pushed out earlier this year.