The fire -- the second in the park in less than a month -- broke out Sunday, fueled by high temperatures and winds in the area, officials said.
The officials did not give any figures about the size of the affected area of the park, which is a key source of water for the Colombian lowlands.
The park -- with snow-capped peaks topping 4,000 meters (13,000 feet) -- is home to several endangered animals, including spectacled bears and tapirs, as well as 20 species of indigenous birds.
An earlier fire in July charred 4,500 hectares (11,000 acres) of vegetation, and experts said it could take 50 years for the flora and fauna to recover.