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NEW: Police say 5 died; fire officials had said previously that 5 were critically injured

The incident happened during a maintenance and cleaning operation, police say

The plant is located in Yokkaichi, Japan

CNN —  

An explosion and fire at a Mitsubishi Materials chemical plant in central Japan on Thursday afternoon killed five people and injured at least 12 others, Yokkaichi police said.

Ealier, the Yokkaichi Fire Department had reported that 17 people had been injured, five critically but did not report any deaths.

The incident happened during a maintenance and cleaning operation at the plant, the Mie Prefecture Police Department said. A fire from the blast lasted about 10 minutes, according to police.

Yokkaichi is located about 320 Kilometers (200 miles) west-southwest of Tokyo.