Four gunmen dressed in fatigues opened fire at a military parade in the city of Ahvaz in southwestern Iran, killing at least 29 people, including women and children spectators and members of the elite Islamic Revolutionary Guards Corps.

The brazen attack on Saturday came as the country marked the anniversary of the start of its 1980-1988 war with Iraq, and prompted President Hassan Rouhani to vow a "crushing response".

Al Jazeera’s Charlotte Bellis reports.

More videos