The northern Iranian city of Qazvin, about 130 kilometres west of Tehran, was rocked by a heavy explosion on Tuesday. Nearly 50 people were reported injured so far. (Google Maps)

A heavy explosion rocked an industrial city in northern Iran on Tuesday, state television said, saying that no one has been reported killed so far.

It cited Governor Saeed Mirbaha as saying there were no deaths in the explosion, but firemen and rescue workers have intensified efforts to control a raging fire that has covered the sky in a large part of Qazvin city.

The city's emergency department said two rescuers had been badly injured from smoke inhalation.

Earlier, the semi-official Fars news agency said the explosion happened in a wood and oil storage facility, leaving nearly 50 people injured — many in serious condition. Many cargo depots are located in the city, some 130 kilometres west of the capital, Tehran.

Fars also said police have closed off roads to the area where the explosion took place, in an old neighbourhood.

More to come