At least 24 people were killed and 53 injured when gunmen opened fire during an Iranian Military Parade in the South-Western City of Ahvaz.
State Media said the attackers shot from a park near the parade and were wearing Military Uniforms.Authorities fear that the death toll could rise further.
Terror Incident occurred when Iran is marking the Anniversary of the beginning of the 1980-88 war with Iraq with several nationwide parades.
Pictures from the scene show wounded soldiers being taken to safety.
The shooting lasted for about 10 minutes, but security forces are now in control of the situation.