A volcano has erupted in southern Colombia, putting local police and emergency officials on high alert.

There were no early reports of injuries or damage from the eruption of the Galeras volcano early Thursday.  But the 30-minute blast of smoke and ash prompted officials to step up calls for people to leave the area. For more than a week, authorities have been urging thousands of residents of the nearby city of Pasto and smaller villages to evacuate.

Reports say some farmers are staying despite the polluted air and the possibility of another eruption, in order to guard their property and livestock.

Located near the border with Ecuador, Galeras has erupted more than 20 times since the area was first settled by European explorers in the 16th century. A 1993 eruption killed nine people.