The Lebanese militant group Hezbollah said Saturday that the explosion in Damascus that killed its top militant commander was caused by insurgent shelling and vowed to continue fighting alongside the Syrian government until the rebels are defeated.

The Lebanese militant group said shelling from Sunni extremists killed Mustafa Badreddine. Hezbollah media had originally blamed an Israeli airstrike.

Israel previously tried to assassinate Badreddine. CCTV’s Stephanie Freid reports.

Badreddine was the highest-ranking Hezbollah militant to be killed since the group joined Syria’s civil four years ago.

Reporting by The Associated Press contributed to this story.