MADRID, Spain (CNN) -- A massive forest fire continued to burn out of control on Monday on the island of La Palma, part of Spain's Canary Islands, a regional government spokeswoman told CNN.
Volunteers look on as a plane drops water on wildfires in La Palma Sunday.
Some 600 firefighters are battling the blaze, backed by aircraft dropping water on the flames, spokeswoman Ana Vidal said. The small island is part of the Canary Islands archipelago located in the Atlantic Ocean off the coast of Morocco.
Firefighters were able to contain the fire on La Palma's western side, but it still raged on the eastern side of the island near the town of Mazo, she said.
Several thousand residents were evacuated but many had returned to their homes by Monday.
More than 6,000 acres (2,500 hectares) have been "affected" by the fire, but not all of that area has been burned, Vidal said. The hilly topography of the lush green island means that some valleys may have burned while others could have escaped harm.
Spanish Prime Minister Jose Luis Rodriguez Zapatero visited La Palma on Sunday and promised aid for those whose homes, businesses, or farms were damaged or destroyed.
"We have a very tough fight this summer," Zapatero said. "All of our collaboration amounts to little because the meteorological conditions in many parts of our country mean serious risk."
A hotter, drier summer has contributed to an increase in fires in Spain this year, according to Spain's Environment Ministry. Spanish firefighters are battling four other forest fires around Spain, with help from the national government. But the largest blaze appeared to be on the island of La Palma.
There have been 9,915 forest fires in Spain during the first seven months of the year which have scorched more than 170,000 acres (69,186 hectares) of land, according to the Environment Ministry.
That is a 26 percent increase in fires, and a 98 percent increase in forest burned from the same period last year.