The Philippines' most active volcano could erupt within days, officials warned Sunday after detecting a drastic surge in earthquakes and eerie rumbling sounds in surrounding foothills. Tens of thousands of villagers have been evacuated as a precaution.

Scientists raised the alert level for the Mayon volcano to one step below a major eruption after 453 volcanic earthquakes were detected in a five-hour span Sunday, compared to just over 200 Saturday, said Renato Solidum, chief of the Philippine Institute of Volcanology and Seismology.

Army troops and police will intensify patrols to enforce a round-the-clock ban on villagers within a five-mile danger zone around the 8,070-foot mountain, said Gov. Joey Salceda of Albay province, about 210 miles southeast of Manila.

The massive evacuations were unfortunate, coming so close before Christmas, Salceda said, but authorities will find ways to bring holiday cheer to displaced villagers in emergency shelters.

The cone-shaped volcano has already belched a plume of grayish ash half a mile into the sky, and red-hot lava has flowed about 2.8 miles down the mountainside, he said.

Residents who briefly returned to their homes within the danger zone to check on their belongings reported hearing eerie rumbling sounds.

More than 40,000 villagers have been moved to school buildings and other emergency shelters, and they should be warned from venturing back now due to the extreme danger, volcanologist July Sabit said.

Superheated gas and volcanic debris can race down the slopes at very high speed, vaporizing everything in their path.

"It's extremely dangerous," Sabit told The Associated Press by telephone.

Residents are used to playing a "cat and mouse" game with Mayon, a popular tourist attraction because of its near-perfect cone shape.

Mayon last erupted in 2006, when about 30,000 people were moved. Another eruption in 1993 killed 79 people.

The first recorded eruption was in 1616 but the most destructive came in 1814, killing more than 1,200 people and burying a town in volcanic mud. The ruins of the church in Cagsawa have become an iconic tourist spot.

The Philippines lies along the Pacific "Ring of Fire," where volcanic activity and earthquakes are common. The Philippines has 22 active volcanoes.