Unconfirmed reports say scores of the workers have reportedly died and many more are injured after an explosion at a chemical factory in southern Iran. 

According to reports by Iran’s state media, a leak in an ammonium tank caused a blast Monday evening in the city of Firouzabad in southwestern Fars province but the blaze was quickly extinguished. 

The chief of the provincial health department, Vahid Hosseini, claims out of 133 injured who were taken to local hospitals, mostly factory workers, 114 were later released after treatment, but witnesses said in social media that 30 to 70 people have been killed in the accident, some of them instantly. 

There are conflicting reports in social media about the cause of the blast, with some saying the tanker was full of nitrogen, not ammonium, hence the high number of casualties. 

Director of Fars Governorate Crisis Management Khalil Abdollahi said on Monday night that the accident is being investigated, noting that nobody died.

Authorities reopened a nearby major road that they had closed after the explosion due to the spread of toxic gas. 

The factory, which went online in August 2020 with over one thousand workers, is a manufacturer of sodium carbonate, a chemical used to build glass, crystal, detergent, cleaning, water purification and in other petrochemical industries. 

Iran occasionally reports fires or explosions at industrial sites that are mainly blamed on technical failures, the result of years of sanctions that have blocked access to new equipment. There have also been many incidents in military sites since mid-2020, with authorities usually blaming Israel.