The Galeras volcano in southeastern Colombia erupted Saturday night, but there were no immediate reports of deaths or injuries, authorities said.
Carlos Ivan Marquez, national aid director for the Red Cross, said officials might need to evacuate 8,000 people as a precaution. He said temporary shelters and aid supplies were available.
The volcano erupted at 7:43 p.m., according to the Volcanology and Seismological Observatory in Pasto, the provincial capital of 500,000 people that is just over 10 kilometers (6 miles) from Galeras.
The 4,276-meter (14,110-foot) volcano has a long history of activity, including several eruptions in the first months of 2009. It sits near the border with Ecuador, some 520 kilometers (320 miles) southwest of Bogota.
Galeras has been considered Colombia's most active volcano since coming back to life in 1989. A 1993 eruption killed nine people, including five scientists who had descended into the crater to sample gases. In November 2005, the volcano spewed ash that fell up to 50 kilometers (30 miles) away.