The death toll is likely to climb higher as more information is revealed. State-run FARS News Agency's live reports have identified up to 30 dead in the aftermath.
The attack follows a similar incident last September, wherein ISIS claimed responsibility for a mass shooting at a military parade which left 29 dead. The last known suicide bombing inside Iran was in 2017, making Wednesday's bombing a rare and devastating event, especially considering it reportedly targeted elite IRGC personnel.
According to early AP and Reuters reports, IRGC troops were aboard a bus when it exploded:
The suicide bomber struck a bus transporting IRGC members on the road between the cities of Zahedan and Khash in Sistan-Baluchistan Province, a volatile area near the border with Pakistan where militant groups and drug smugglers frequently operate, Fars reported.