Gov Huseyin Avni Mutlu ruled out any terrorist attack and said the blast was caused by a gas leak or a gas canister.
The explosion in a packaging workshop on the ground floor of the building caused a fire which was quickly extinguished, the private Dogan news agency reported.
Hurriyet newspaper said the injured included a pregnant woman who jumped from a balcony on the second floor of the building. It said some cars were overturned by the force of the blast.