Authorities are struggling to contain a fire which has broken out in a chemical factory in the western state of Maharashtra, killing three people.
The fire in Boisar near Mumbai city has also injured several, police said.
Police have cordoned off the area and rescue and search operations are still underway.
Authorities expect the number of casualties to rise and medical teams are at the spot, police confirmed to the BBC.
Local eyewitnesses told Indian media that the fire followed an explosion that “sounded like a huge bomb” late on Thursday night.
The “tremors” caused by the explosion were felt nearly 12km (7 miles) away, shattering windows even in some Mumbai areas, the reports added.
Earlier this year, Mumbai saw two buildings catch fire in within a week which have since raised serious questions over standards of safety in the city.