A day after announcing the death of its top military commander in Syria, Lebanon-based Hezbollah said Saturday that an artillery explosion triggered by jihadist insurgents killed Mustafa Badreddine. The Shiite Islamist group blamed “takfiri groups”— a term it uses to refer to armed, hard-line Sunni Islamist groups — for the death of Badreddine.

“Investigations have showed that the explosion, which targeted one of our bases near Damascus International Airport, and which led to the martyrdom of commander Mustafa Badreddine, was the result of artillery bombardment carried out by takfiri groups in the area,” Hezbollah said in a statement, cited by Reuters.

Hezbollah has been involved in the fighting in Syria, where it supports the regime of President Bashar Assad. About 1,200 members of the group, which is backed by Iran, are thought to have died in Syria’s civil war while fighting against the Islamic State group and the al Qaeda-linked Nusra Front.

The group said Friday it was investigating the cause of the explosion that killed Badreddine.

The statement released Saturday said: “The result of the investigation will increase our commitment and will and perseverance in continuing to battle these criminal gangs and defeat them.”

Badreddine was purportedly running all of Hezbollah’s military operations in Syria since 2011, the BBC reported.