At least nine trekkers have died in a forest fire in the southern Indian state of Tamil Nadu, officials say.

Authorities say they have rescued 21 people from the Kurangini hills - a popular trekking destination - where the fire broke out on Sunday, wrote BBC.

Many of those injured have suffered severe burns and are receiving treatment at a nearby state hospital.

The military was deployed to help with rescue efforts after the state government asked for assistance.

Six people are still believed to be trapped in the blaze.

"It has been difficult to rescue people since the incident occurred in the night and there are landslides in the region," senior official Pallavi Baldev told reporters.

"But the medical team is rushing to provide first aid to those already rescued."

One of those rescued, Illakiya Chandran, 29, had been on the trek to celebrate international women's day with her friends. She was rescued after she walked for more than two km in the forest with her injuries, her husband Stalin Shankar told BBC Tamil.

"She was saved only because of her will power," doctors said.

Another of those rescued, Vijayalakshmi, told BBC Tamil that she had a "lucky escape".

"We were on the hill trail of the Chennai trekking club and some of us were caught in the fires," she said. "I also got burned, but luckily we were able to escape."

Civilians from the area had also been assisting in rescue efforts, local media said.

The injured have been taken to the closest government hospital in Madurai city and plastic surgeons will provide treatment free of cost, state health secretary J Radhakrishnan told BBC Tamil's Pramila Krishnan.

The trek was organised by a club in the state capital Chennai and had begun on 9 March.