Lebanon's militant Hezbollah group says its top military commander was killed in Syria by insurgents shelling.

The group says the blast that killed Mustafa Badreddine near the Damascus International Airport was caused by artillery shelling by "takfiri" groups, a term Hezbollah uses to refer to Sunni extremists.

The group said in a statement Saturday that Badreddine's killing will only boost Hezbollah's "will and intention to continue fighting these criminal gangs."

Hezbollah has sent thousands of fighters to Syria to back President Bashar Assad's government against militants trying to remove him from power.

The group announced Badreddine's death on Friday without saying when the attack occurred. It said the group opened an investigation to know the reason behind the blast.