Iran's semi-official Tasnim news agency says a Sunni cleric who had worked to reconcile Sunnis and Shiites, members of the two biggest sects in Islam, was shot and killed.
The report says the cleric, Abdolghafour Jamalzai, was shot in the back with a hunting rifle on Tuesday morning outside of a mosque in the town of Gorgan. The town is about 300 kilometers northeastern of Tehran.
The report didn't say how many gunmen were involved or speculate on the possible motives for the assassination.
No group claimed responsibility for the attack.
Tasnim says the cleric believed that enemies of Islam are trying to stir up trouble between Shiites and Sunnis. Iran is a majority Shiite nation.
In July, gunmen assassinated a Sunni cleric in southeastern Iran.