Three assailants were also killed in the ensuing clashes with security forces, a senior police official told the state news agency IRNA.

He said a mother and child were among those killed by the gunmen who threw a hand grenade into the building in Zahedan, the capital of Sistan-Baluchestan.

In a statement posted on its Telegram account, Jaish al-Adl took responsibility for the attack and urged “all civilians to immediately evacuate the area of clashes for their safety”.

The Baluch human rights group Haalvsh, quoting eyewitnesses, said several judiciary staff members and security personnel were killed or wounded when the assailants stormed the judges’ chambers.

Sistan-Baluchestan province, near the borders with Pakistan and Afghanistan, is home to Iran’s Sunni Muslim Baluch minority, who have long complained of economic marginalisation and political exclusion.

The province frequently sees clashes between security forces and armed groups, including Sunni rebels and separatists who say they are fighting for greater rights and autonomy. The Iranian government accuses some of them of ties to foreign powers and involvement in cross-border smuggling and insurgency.