A fire call was received at 4.45 PM and 20 fire tenders were rushed to the spot, said a fire department official.
Later five more fire tenders were rushed to control the blaze that had started in the three-storeyed factory, he said.
While the operations were on, the top floor of the building collapsed and six people, including two fire department officers, were trapped under the debris, police said.
Four of the injured people have been evacuated and rushed to a hospital. Efforts were on to rescue two others trapped under the debris, a senior police officer said.
The cause of the fire is suspected to be an electric short-circuit, police said.
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