Tehran, Jan 22 (IANS): A massive blast was heard on Monday morning at an industrial park in the central Iranian city of Garmsar, Semnan province, the semi-official Mehr news agency reported.
The source of the blast had not been determined yet, the report said, adding local authorities had sent rescue teams to the industrial park, Xinhua news agency reported.
According to Mehr, this is the fourth incident in Semnan province's industrial parks and areas over the past few days.
Four people had been killed in the previous incidents.