Some unconfirmed reports say at least three people were killed in the incident.
The explosion also led to the serious injuries of several people who have been transferred to hospital for treatment.
The cause of the explosion was not immediately clear.
Esfahan Steel Company is Iran’s third largest steel producer and is directly controlled by the ministry of industry, mine and trade.
In a similar incident in 2011, seven workers were killed at a steel production complex in central province of Yazd. Also 12 others were injured in that incident.
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