With two more persons succumbing to their injuries at a hospital on Monday, the death toll in the March 17 explosion in a gold ornaments-manufacturing unit at Mulangu in Thrissur district has risen to seven.

The deceased were identified as Haridas (48) and Biju Krishnan (33), police said.

The explosion occurred while transferring cooking gas from a large cylinder to smaller ones on March 17 at the unit.

While one person died on the spot, others died on subsequent days. Five persons are still undergoing treatment for burn injuries suffered from the explosion, they said.

The unit was running without proper permission and no safety precautions were taken, police said.

Charges have been framed against the owner of the unit, Kottikkal Saleesh under IPC 304 (culpable homicide) and various sections of the Indian Explosives Act.

He was arrested on March 19 and remanded to judicial custody.

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