It's the latest in a mysterious string of blasts and 'accidental' blazes at sensitive sites to beset the Islamic Republic, raising questions of possible Israel sabotage akin to what happened a year ago in the summer of 2020. 

"The governor of Zarand told the Iranian Fars News Agency that no injuries were caused in the incident and that the incident was under control," The Jerusalem Post reports. "The incident was reportedly caused by the sudden overflow of molten material in the blast furnace, with the governor stressing that no explosion occurred." But some early videos show otherwise.

Social media videos showed a sizable blaze which appear to have triggered a significant explosion, however, resulting in debris and what looks like molten steel flying into the air.