The woman died in the burns clinic of Makhachkala's central hospital on Friday evening, a day after the explosion at the Dagnefteprodukt oil depot. Firefighters battled with the blaze for almost 24 hours.
"The 29-year-old operator injured in the explosion was in a critical condition. She had third and fourth-degree burns, burns to her respiratory tract, and third-degree shock. There was almost no chance of saving her," a spokesperson said.
Daghestan's emergencies ministry will hold a news conference on March 31, and may give details on the criminal investigation into the cause of the blast.
According to preliminary information, the explosion was caused by human error, and was not a terrorist attack.