Gunmen attacked a major Shiite holy site in Iran on Wednesday, killing at least 15 people and wounding dozens. The attack came as protesters elsewhere in Iran marked a symbolic 40 days since a woman's death in custody ignited the biggest anti-government movement in over a decade.

State TV blamed the attack on “takfiris,” a term that refers to Sunni Muslim extremists who have targeted the country's Shiite majority in the past. The attack appeared to be unrelated to the demonstrations.

The official website of the judiciary said two gunmen were arrested and a third is on the run after the attack on the Shah Cheragh mosque, the second holiest site in Iran. The state-run IRNA news agency reported the death toll and state TV said 40 people were wounded.