A massive blaze swept through a fireworks factory in southern India on Wednesday, killing at least 40 workers and injuring 60 others, police said. Some reports put the death toll at more than 50.

The fire spread to 40 of the 60 rooms at the Om Siva Shakti fireworks factory, one of the biggest in Sivakasi town in Tamil Nadu state, police officer P. Karupaiah said.

Witnesses said flames billowing out of the factory could be seen 1.5 kilometers (one mile) away. Firefighters with about a dozen fire engines extinguished the fire after about five hours, news reports said.

The Press Trust of India news agency said about 300 people were working in the factory and 52 died. The CNN-IBN television news channel said rescue workers had completed a search of the devastated building for any more trapped workers.

Large amounts of firecrackers and raw materials were stored in the factory with major Hindu festivals weeks away.

The cause of the fire was not immediately known, Karupaiah said.

Sivakasi is about 500 kilometers (310 miles) southwest of Chennai, the state capital.

The region has many factories making fireworks, which are used in religious festivals and weddings across India. They also are exported to other Asian countries. Some illegal fireworks factories operate in homes.