At least three persons were killed and seven others injured in a series of explosions at a private ammunition factory in the forests of Rajpur on the outskirts of Dehradun on Thursday morning.

The blasts were so powerful that their impact was felt in the whole of Dehradun city with windows and doors of houses rattling. A mini mushroom cloud formed in the sky immediately after the blasts.

Nearly a dozen fire tenders were pressed into service to douse the fire in the factory that supplies explosives to various defence ordinances factories.

The chain of explosions also blew off the whole building where a group of workers were sieving ammunition powder, the police said.

Due to the impact of the blasts, the bodies of two workers were thrown at a distance of nearly 400 to 500 meters away from the site of the explosions.

All the three deceased were the workers of Narendra and Company, which runs a factory inside the Rajpur jungles on the outskirts of the city, SSP, Dehradun, Sanjay Gunjyal said.

Among the seven injured, the three seriously wounded were rushed to government Doon hospital where their condition was stated to be serious.

Sanjay Thakur, a survivor, who was also working at that time inside the factory, said nearly 150 kg of ammunition was stored where the blasts occurred.

Gunjyal said police has ordered an inquiry into the blasts. "There are reports that the factory had stored more ammunition than its capacity. We are also investigating this angle," he said.