The witnesses said that the blast took place in the Shair Colony area of Sopore, 48-km from capital Srinagar when a scrap dealer was downloading some old metal from a load-carrier on Monday afternoon.
Four persons including two children injured in the impact of the blast were rushed to a nearby hospital where doctors declared three of them dead. The fourth injured person was referred to Srinagar's Sher-i-Kashmir Institute of Medical Sciences (SKIMS) for specialised treatment, but he too died on the way, the police sources said.
The deceased have been identified as Nazir Ahmad Nadroo, Azam Ashraf Mir, Abdul Rashid Bhat and Adil Rashid Bhat.
The police also said that they have registered a case under the relevant provisions of the law and taken up investigation. A few persons are being questioned at the concerned police station, the local sources said.
Meanwhile, about 30 people were injured after a mini bus overturned at Khuga Morh on the outskirts of Jammu city on Monday.
The officials said that the mini bus, on its way to the border town of Akhnoor from a place called Maira Mandrian, was being driven at a high speed when it skidded off the road and turned turtle near Khuga Morh.
Ten of the injured were shifted to Jammu's Government Medical College Hospital whereas the others who had received minor injuries were treated locally, the officials added.