Video of massive firing of Basij and IRGC forces in Khuzestan in front of daring protesters.

Khuzestan is the major oil-producing region of Iran, and as such is one of the wealthiest provinces in Iran. 

Much of the population are ethnic Arabs who wish to break off from Iran. The connection between them and Israel is good and known.

As you can see from the map - this area is of huge importance to Iran as it is on shores of the Persian Gulf.

Source: Sam Rajabi - Twitter