A wildfire raged Monday on Spain's Canary Island of La Gomera which burnt down several homes and raced through a national park housing a rare subtropical forest, officials said. Deep ravines made it difficult to fight the blaze, which erupted on Saturday and has affected 3,100 hectares (7,400 acres) of land, including 350 hectares, or nine percent, of the Garajonay national park, a World Heritage Site. "The ravines act as genuine chimneys for the fire when the wind blows and this complicates the task of getting the fire under control," the head of the islands' government, Paulino Rivero, told reporters. By late Monday firefighters, aided by cooler temperatures and higher air humidity levels, had managed to stop the advance of the flames at Garajonay, the regional government said in a statement. The national park was added to UN cultural body UNESCO's World Heritage list for its rare subtropical forests which covered the Mediterranean millions of years ago but have now largely disappeared. It is home to 450 plant species, including eight that are found only in the park. At Igualero, a village inside the park whose residents were evacuated over the weekend, several houses were completely burned down. The burned down homes were surrouned by charred fruit trees, vineyards and potato crops as well as the dead sheep, goats, chickens and other animals. Several homes near the town of Vallehermoso had been destroyed, mayor Jaime Luis Noda said. "We have still not done an evaluation of exactly how many, so we don't know how many," he said. Mobile telephone services on the island were disrupted as several relay stations had burnt down, power was out in some parts of the island and four roads where shut, the regional government said. But around 600 people who were evacuated over the weekend, including those at Igualero, were allowed to return to their homes Monday. Heavy fog on Monday morning prevented two firefighting aircraft sent from mainland Spain from flying but by afternoon the authorities were able to use water-dropping aircraft against the blaze, which has three active fronts. The authorites suspect arson as the cause of the blaze "because it started in three different places and it is practically impossible for an accident to trigger such a violent fire," he added. A shepherd on the island of La Gomera, Sebastian Vera Herrera, said many of his sheep were killed by the flames after he ignored police orders to evacuate. "I guided them to the farm in the hamlet of Magana. Many sheep burned. I managed to save many, about 300 because I stayed," the 58-year-old said. "This is the first time that I have seen a fire likes this, of this size. There are 200-year-old houses that completely burned down." Another fire on the neighbouring island of La Palma near the town of Mazo has been stabilised. That blaze had affected about 1,700 hectares. Spain has been battling fires in both the Canaries and on the mainland after a winter that saw almost no rainfall, leaving the Spanish landscape its driest in seven decades. On July 22, a wind-whipped wildfire in the northeast province of Catalonia near the border with France scorched 14,000 hectares, claiming four lives. Spain's most destructive fires so far this year were in the Valencia region in early July, burning some 50,000 hectares of vegetation.