Philippines' Mayon Volcano spews lava as locals prepare to evacuate in case of explosion

The Philippines' most active volcano was gently spewing lava down its slopes Monday, alerting tens of thousands of people they may have to quickly flee a violent and life-threatening explosion.

More than 12,600 people have left the mostly poor farming communities within a 6-kilometer (3.7-mile) radius of Mayon Volcano's crater in mandatory evacuations since volcanic activity increased last week. But thousands more remain within the permanent danger zone below Mayon, an area long declared off-limits to people but where generations have lived and farmed because they have nowhere else to go.

With the volcano beginning to expel lava Sunday night, the high-risk zone around Mayon may be expanded should the eruption turn violent, said Teresito Bacolcol, director of the Philippine Institute of Volcanology and Seismology. Bacolcol said if that happens, people in any expanded danger zone should be prepared to evacuate to emergency shelters.