A thousand people were evacuated and traffic was stopped after the Galeras volcano erupted in southern Colombia without causing casualties, officials said Saturday. The locals were taken to shelters in Pasto, the capital of Narino department on the border with Ecuador, after authorities put the volcano -- the most active in Colombia -- on red alert to signal an imminent or ongoing eruption. Some 9,000 people live in the vicinity of the volcano, which erupted at 8:37 pm Friday (0137 GMT Saturday), will be forced to leave their homes and seek refuge in temporary accommodations if the alert is prolonged, the Colombia Institute of Geology and Mining (Ingeominas) said. Narino Government Secretary Fabio Trujillo, whose office coordinates volcano prevention, evacuation and relief efforts, told local radio that traffic restrictions would be imposed on the highway linking Pashto -- 920 kilometers (570 miles) -- to localities close to Galeras. The eruption caused ashfall in Pashto and surrounding villages, according to local media. A 1993 eruption of Galeras, which rises in the Andes mountain chain to an altitude of 4,270 meters (14,029 feet), killed nine people, including six scientists who had descended its crater to take gas samples. Ingeominas says the volcano was reactivated in 2004 and causes about 19 earthquakes per year. Authorities said they are continuing to monitor the nearby Huila volcano, on orange alert, where sizeable volcanic activity also has been detected in recent weeks. Huila, at some 5,363 meters (17,595 feet), last erupted in November 2008, killing 10 people.