Massive forest fires are sweeping through the north Indian state of Uttarakhand and have killed at least seven people in recent weeks with no signs of abating.

The Indian government joined state firefighters over the weekend in trying to douse the blaze. Air force helicopters were deployed Sunday to drop water on the fires tearing through hundreds of acres (hectares) of pine forests.

State Forest Officer Bhanu Prasad Gupta said the scattered fires were spreading and were threatening two of the country's major tiger conservation reserves.

Federal Environment Minister Prakash Javdekar said Monday that four men have been arrested over the weekend for starting forest fires.

Two consecutive years of poor monsoons have led to dry conditions making vast areas vulnerable to forest fires.