Eight people were injured, two of them severely, in an explosion on Thursday at a scrap dealer's shop in the Raipur area of the city, police said.
The explosion apparently took place when someone was sorting the scrap, according to the Raipur police station.
A fire unit and a bomb disposal squad were rushed to the spot, Superintendent of Police (City) Pramod Kumar said, adding that the blast took place after 2 pm.
An ordnance factory and a firing range are in the same area and it is suspected that the blast might have been caused by an unexploded mortar shell brought to the shop.
Police, however, did not confirm this.
Uttarakhand Congress senior vice-president Suryakant Dhasmana, who met with the injured, said the blast took place when a boy tried to break an object with a hammer.
Five of the injured were undergoing treatment at the Doon Hospital and the condition of two of them is stated to be serious, Kumar said.
Three others who sustained minor injuries were admitted to the Coronation Hospital, he said, adding that investigations were on to find out what led to the blast.