At least fifteen workers died in a fire at a chemical plant in Maharashtra’s Pune district on Monday, The Indian Express reported. Many were still feared to be trapped inside.

The fire broke out at the plant belonging to SVA Aqua Technologies in Pune’s Mulshi taluka. The plant deals with water, air and surface treatment chemicals, The Times of India reported. Visuals on social media showed thick plumes of smoke emanating from the facility.

Pune District Collector Rajesh Deshmukh confirmed the toll and said that the fire has been brought under control but many areas of the factory were not accessible yet.

“The search is still on and the [death] count may go up,” Deshmukh said. “The total casualty will become clear only after the entire area is searched.”

Thirty-seven workers were inside the plant when the fire broke out, Devendra Potphode, the head of Pune Metropolitan Region Development Authority fire brigade, told The Indian Express.

“As per the roll call, initially a total of 17 including 15 women and two men were missing, the official had said, earlier on Monday.

At least six fire tenders were sent to the plant to douse the flames, PTI reported. The Pune rural police were also at the spot to manage the crowd outside the facility, according to The Indian Express.

Fire brigade personnel had to break the walls of the plant to get inside the premises, The Times of India reported.

Potphode said that according to the facility’s officials, the fire started while the workers were packaging plastic materials, PTI reported. “Due to some spark at the [packaging] section, the fire broke out and as there was plastic around, it spread rapidly,” he added.