One of South America's most active volcanoes erupted early Tuesday in southern Chile, spewing heavy smoke into the air as lava surged down its slopes, prompting authorities to evacuate thousands of people. Authorities worried that mudslides caused by melting snow could endanger nearby communities.

The Villarrica volcano erupted around 3 a.m. local time, according to the National Emergency Office, which issued a red alert and ordered evacuations. Local media showed images of the volcano bursting at the top, glowing in the dark amid heavy smoke and rivers of lava.

The 9,000 foot volcano in Chile's central valley, 400 miles south of Santiago, sits above the small city of Pucon, which has a population of about 22,000 people.

Chilean authorities had issued an orange alert on Monday because of increased activity at the volcano. About 3,500 people have been evacuated so far, including tourists, said Interior and Security Minister Rodrigo Penailillo.

Penailillo warned that the eruption had caused numerous rivers in the area to rise as snow along the sides of the volcano began melting.  Villarrica is covered by a glacier cap covering some 15 square miles and snow from about about 5,000 feet on up.

Authorities were keeping an eye on four nearby communities that could be endangered by mudslides as the snow melts.

Tourists flock to the area around Villarrica for outdoor activities like kayaking, horseback riding, fishing and hiking around the volcano, which last had a major eruption in 1984. Dozens of tourists were among those evacuated.

President Michelle Bachelet announced that she will travel to the volcano-hit area to check on safety preparations and asked residents to remain calm.

The Villarrica has a crater of about 200 yards in diameter and a lake of lava about 150 yards deep. It has periodic eruptions every 10 or 15 years.

Chile has more than 2,000 volcanoes in the Andes cordillera and about 90 of them remain active. Villarrica is considered among the country's most dangerous.