At least eight people, namely five civilians and three assailants, were killed and 13 others were injured in a "terrorist" attack Saturday morning on the building of the justice department in Iran's southeastern city of Zahedan, the capital of Sistan and Baluchestan province, the semi-official Tasnim news agency reported.

Responsibility for the attack has been claimed by Jaish al-Zulm, designated by Iran as a terrorist group, the report said.

It added that upon entering the justice department's premises, the "terrorists" opened fire on the people there, stressing that the casualties could further increase.

Iran's Islamic Revolution Guards Corps (IRGC) said in a statement published on its official news outlet Sepah News that its ground forces managed to kill three of the "terrorists."

The IRGC added that some of those injured in the attack were in critical condition, giving the assurance that security forces had the situation under control.

In remarks to Tasnim, Mohammad-Hassan Mohammadi, head of Zahedan University of Medical Sciences, said all the wounded were transferred to nearby hospitals.

Provincial authorities have called on people to stay away from the justice department and the surrounding areas.

Jaish al-Zulm has been involved in many deadly attacks against Iranian security forces and civilians in recent years