A huge inferno ripped through an industrial city in Qom, Iran, on Sunday.
The semi-official Fars News Agency broadcast images of a column of smoke from the Shokuhieh Industrial Zone towering over the city, 140 kilometres south of the capital, Tehran.
Six firefighters were reportedly injured responding to the blaze, one of them critically.
The industrial zone has a number of petrochemical companies which make a variety of plastic products.
Iran's Isna news agency reported that the fire was at the Movaledan chemical factory. Twenty fire engines and 100 firefighters were sent to tackle the blaze, according to Qom Fire Department spokesman Hamid Karimi.
Mr Karimi said firefighters fought to stop the flames from reaching explosive substances, including alcohol.
Rumours of sabotage
Although it is too early to speculate on the cause of Sunday's fire, last year Iran experienced several large-scale industrial accidents, as well as a spate of mysterious fires, including a gas pipeline explosion.
The industrial incidents followed several mysterious explosions at Iranian nuclear sites.
Ali Akbar Salehi, the head of Iran's Atomic Energy Organisation, blamed the nuclear incidents on Israeli or US cyber attacks, but Tehran was more guarded on possible causes of the industrial incidents, which peaked in the summer and autumn of last year.
The official Islamic Republic News Agency said Israel was responsible, but government statements were more cautious, blaming Israel for attacks at the Natantz nuclear facility, but not the industrial sites.
In July last year, an inferno in the southern Iranian port city of Bushehr gutted seven ships docked in the port. The same month, an aluminium factory in the industrial city of Lamard, in Fars province, caught fire.
And within 24 hours on July 12-13, a petrochemical plant in Mahshahr and an industrial complex in Mashhad suffered explosions.
A power station in Isfahan also suffered an explosion about the same time.
All of these attacks occurred alongside explosions at Natanz and Parchin, nuclear and military research sites, respectively.
Israel has consistently followed a policy of not admitting involvement, at least publicly.
Privately, Israeli officials are said to have claimed responsibility for nuclear sabotage attacks, leaking information to publications including the New York Times and the Wall Street Journal while also claiming sabotage attacks on Iranian ships at sea.
Publicly, Israel appears to seek a level of ambiguity about its possible involvement.
“Not every incident that transpires in Iran necessarily has something to do with us,” Israeli Defence Minister Benny Gantz told Reuters in July last year.
