Advertisement - story continues below
An immense explosion has been heard throughout the northern Iranian city of Qazvin, semi-official Fars news agency reported, and many casualties are expected from the blast.
Around 1.1 million people live in the city, which is located about 100 miles north of Tehran.
The blast may be related to nuclear development in Iran, according to the Los Angeles Times. Iranian officials in the past have strongly denied claims by Mujahedin Khalq Organization, or MKO, a cult-like Iranian exile group, that it has a secret nuclear enrichment facility in Abyek, near the major city, according to the daily.
The source of the blast remains undetermined. Several mystery explosions have been reported in the past several years in the region, none of which were ever verified.
Several casualties were reported. Roads leading to the site of the fire within a 2km radius have been closed off.
Macedonian News Service reported:
A heavy explosion has taken place at a warehouse in Qazvin, north Iran, according to local news agencies. Authorities expect high numbers of casualties as a subsequent fire tore through the area.
Unconfirmed local reports state that as many as 50 could have been either killed or injured in the city, which is considered a commercial hub.
A fire broke out, engulfing the city in a cloud of smoke. Roads leading to the site of the fire within a 2km radius have been closed off and people evacuated, according to the semi-official Fars news agency.