The toll in the blast at an illegal firecracker factory in West Bengal's Purba Medinipur district rose to 12 after two more persons succumbed to their injuries, a senior official said on Saturday.
Rabindranath Maity and Pinki Maity, who had third-degree burn injuries, died at the state-run SSKM Hospital in Kolkata where they were undergoing treatment, he said.
"Rabindranath died on Friday night and Pinki succumbed to her injuries on Saturday afternoon. Their conditions were deteriorating constantly since they were brought here," the official said.
Prime accused and owner of the illegal firecracker manufacturing unit, Kalipada alias Bhanu Bagh, who was arrested by the West Bengal CID on Thursday, had succumbed to his injuries at a private nursing home in Odisha's Cuttack, where he had fled soon after the blast on May 16.
Nine people were killed soon after the explosion took place at the unit in Egra.
The West Bengal CID, which is investigating the case, has so far arrested nine people.
Meanwhile, the National Human Rights Commission (NHRC) on Friday issued a notice to the West Bengal government, seeking a detailed report on the explosion within four weeks.