The incident took place at the compound of the state-owned Mechanical and Chemical Industry Corporation factory in the Elmadag district, east of the capital, Ankara.
The cause of the explosion was not immediately known, though the governor of Ankara, Vasip Sahin, said it was likely due to a chemical reaction during dynamite production.
Sahin told reporters that no more workers were trapped, or waiting to be rescued, or sent to hospital.
An investigation is underway, with several ambulances and firefighters sent to the factory.
The families of those working in the compound have been gathering there to find out more.
The blast was so forceful that it shattered windows in shops and houses nearby, Turkey's NTV news channel reported.
The factory produces missiles for the Turkish Armed Forces and the Turkish Ministry of Internal Affairs.