The explosions, in a worst-case scenario, could countinue for two or three days, one official said.
The Russian Emergencies Ministry said 11 people were hospitalized and more than 6,000 residents were evacuated from their homes in a Samara Region village near the depot Tuesday, RIA Novosti reported.
The fire at the Volga Federal Ammunition Testing Site was followed by a series of explosions, which continued to rock the area, sending shrapnel more than a half-mile from the blast site, the ministry said.
A ministry spokesman told RIA Novosti the depot had about 6,000 122-mm artillery shells and other ammunition and explosives,
Investigators said a wildfire could have sparked the blaze at the testing facility.
The Emergencies Ministry said the village wasn't under a chemical threat.