MANILA — Philippine officials raised the alert level on the Mayon volcano on Monday as it began spewing an ash plume more than 4,000 feet high from its summit in a spectacular show of destructive power.

The Philippine Institute of Volcanology and Seismology has raised the alert level to four — the highest is five — meaning the cone-shaped volcano was in a stage of “intense unrest” that could set off a hazardous eruption at any time.

The volcano generated up to 1,600 feet of lava fountains before dawn Monday, lighting up the dark sky with an intense crimson glow. At least two nearby villages experienced ash fall, the volcano institute said.

“The lava fountains signified an increase in mass eruption rate, as lava was observed to be flowing more voluminously than before,” it said, adding that lava flows had spread more than two miles from the crater.