The blast occurred in Gujarat's Bhavnagar district on Sunday and injured nine workers, police said.
Approximately one hour and a half earlier on Saturday evening, a fire broke out at Arihant Furnace Rolling Mill located near Sihor town in the district, nearly 200 km from Gandhinagar, a police official said.
The blast occurred suddenly in the factory, while nine workers were present.
Officials said they were all taken to a government hospital in Bhavnagar and are trying to find the cause of the blast.