Forty hectares are afire in the state nature reserve Denezhkin Kamen in the Sverdlovsk Region. Twenty three people fight the blaze with the use of four vehicles, the press service of the Russian Emergencies Ministry's regional centre told Itar-Tass on Friday. Ground lines are plowed around the territory to prevent the blaze from spreading. The area is difficult to reach by vehicles. The fire is fought with knapsack fire extinguishers, the press service said. A team of volunteers is formed to help fight the blaze. There is no threat to residential areas. What caused the fire is being investigated.