"Mujib Rahman Ansari, with some of his guards and civilians, have been killed on their way toward the mosque," said Herat's police spokesperson Mahmood Rasoli.
Ansari had been attacked by a suicide bomber on his way to the mosque from his home, Rasoli added.
The Taliban's spokesperson Zabiullah Mujahid, in a Tweet expressed "strong condolences" over Ansari's death and said his attackers would be punished.
There was no immediate claim of responsibility but previous mosque attacks have been claimed by Daesh [the Arabic acronym for terrorist ‘ISIS/ISIL’ group], which has carried out a series of attacks against religious and ethnic minorities in Afghanistan.