A fire broke out at a flex and hologram manufacturing unit in Sector V on Friday afternoon, police said.

Thick smoke covered Salt Lake’s eastern skyline. Eleven fire tenders took around two hours to bring the blaze under control.

An explosion in the building aggravated the flames that leapt out of the factory and spread across the compound.

State fire minister Sujit Bose and Bidhannagar police commissioner Mukesh visited the spot.

There were no reports of anyone being trapped or injured in the fire.

The cause of the fire could not be ascertained till late on Friday, the police said.

The fire did not spread out of the factory compound and could be accessed by the firefighters from an adjoining building.

“The fire has been doused. Several documents and files have been retrieved, but a major portion of the unit was destroyed,” said a fire department officer.

Three padlocks were put on the factory gate by the police and the fire department.

Sources said the padlocks would be opened only after a forensic team reaches the spot for an examination after the factory compound cools down.