A video published on social media showed people standing among debris and wrecked cars in front of a damaged building following the explosion.
HRANA and the state-affiliated Tasnim news agency reported that authorities had detained the administrator of online accounts urging protests.
The sharp rise in detentions and deportations has sparked renewed criticism from rights advocates inside Iran.
Afghan authorities in Herat and Nimroz have reported growing pressure on local services and have appealed for greater international support to assist returnees.