A bomb explosion occurred at the shrine of Ali al-Ridha, the eighth Imam of Shia, on 20 June 1994 in a crowded prayer hall in Mashhad, Iran.

To maximize the number of casualties, the explosion took place on Ashura, one of the holiest days for Shia muslims,[3] when hundreds of pilgrims had gathered to commemorate the death of their third Imam, Husayn ibn Ali.

[11] However, Raymond Tanter, a member of the United States National Security Council under President Ronald Reagan, believes that MEK was not involved, and that a Pakistani militant connected to Yousef was the perpetrator.

[2] According to the National Council of Resistance of Iran, in a trial in November 1999, Interior Minister Abdollah Nouri claimed it was a false flag attack by the Iranian regime to blame MEK.

[14][failed verification] A 2013 play entitled "the picture of Aziz's event" narrated the life of a woman who was going to visit Imam Reza shrine on the day of the bombing.