Emergency Situations Ministry spokesman Sergei Vlasov said on Wednesday that preliminary investigations indicated that a technical problem sparked the explosions at the depot in the town of Noginsk, about 60km east of Moscow.
The blasts ripped through a chemical laboratory at the depot at around 5.50am. The storage facility supplies the capital and its suburbs.
Two tanks of petroleum products inside the lab then caught fire, and the blaze spread to four nearby cargo rail cars that contained oil products.
Aljazeera has learned that about six tons of fuel were in the tanks at the time.
Two laboratory workers were killed and one was in critical condition, Vlasov said.
The fire had been contained by 9.30am but not before it had spread to a nearby maternity hospital, where nearly 200 patients and workers had to be evacuated, he said.
More than 800 people from nearby apartments and a school were evacuated.
Emergency workers dispatched a helicopter and specially-outfitted firefighting train to the scene.
The reports gave no indication that the authorities were considering terrorism as a cause, but Chechen rebel groups have targeted utilities, theatres and other facilities in the past to publicise their cause.
On Sunday, a bomb caused four carriages on a train travelling from the Chechen capital, Grozny, to Moscow to derail about 150km south of Moscow. No one has claimed responsibility.