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.

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"What we are seeing now is an effusive eruption," Bacolcol told The Associated Press. "We are looking at this on a day-to-day basis."

From a distance, Associated Press journalists watched lava flow down the volcano's southeastern gullies for hours Sunday night. People hurriedly stepped out of restaurants and bars in a seaside district of Legazpi, the capital of northeastern Albay province about 14 kilometers (8.5 miles) from Mayon, many of them snapping pictures of the volcano that's a popular tourist draw known for its picturesque conical shape.

Albay was placed under a state of emergency Friday to allow for quicker distribution of any disaster relief funds in the event of a major eruption.

The volcano had been raised to alert level three on a five-step system Thursday, warning that the volcano was in a state of high unrest and a hazardous eruption is possible in weeks or days.

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With lava flowing down from the volcano gently, Bacolcol said the alert level would stay at three but it could be moved up higher if the eruption turns perilous.

The highest alert, level five, would mean a violent and life-threatening eruption is underway with ash plumes shooting into the sky and superheated pyroclastic streams endangering more communities at Mayon's lush foothills.

Mayon is one of 24 active volcanoes in the Philippines. It last erupted violently in 2018, displacing tens of thousands of villagers. In 1814, Mayon's eruption buried entire villages and reportedly left more than 1,000 people dead.

Many of Albay's people, however, have accepted the volcano's sporadic fury as part of their lives.

On Sunday morning, throngs of people jogged, biked and walked their dogs in a seaside promenade in Legazpi. The 2,462-meter (8,077-foot) volcano lay hidden in thick clouds at a distance.

Some locals have grown wealthy from the tourism industry that has sprung from Mayon or the gravel, sand and ornamental rocks and boulders found around the volcano in abundance.

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Inside the permanent danger zone, authorities and villagers on Sunday were moving cows and water buffaloes from the high-risk farms to temporary grazing areas a safe distance away.

"It's not only people that should be brought to safety but their farm animals, too," Albay provincial veterinarian Manny Victorino told AP. He said authorities were taking steps to avoid a deeper economic impact should the volcano erupt.

They gave deworming medicine and vitamins and punched identifying tags onto the ears of several cows and buffaloes for better monitoring.

The cattle evacuations underscore how wide the potential threats are from natural disasters in the Philippines.

The archipelago is lashed by about 20 typhoons and tropical storms a year and is located on the so-called Pacific "Ring of Fire," the rim of seismic faults where most of the world's earthquakes and volcanic eruptions occur.

In 1991, Mount Pinatubo north of Manila blew its top in one of the biggest volcanic eruptions of the 20th century, killing hundreds.