Lava and broad columns of ash illuminated by lightning spewed from a volcano south of the Philippine capital this morning, grounding hundreds of flights as authorities warned of a possible "explosive eruption".
Fine grit coated homes and streets across the region surrounding the Taal volcano, which burst to life yesterday accompanied by a series of earthquakes, forcing at least 10,000 people to seek refuge in evacuation centres.
Taal, situated in a lake, is one of the most active volcanoes in a nation where earthquakes and eruptions are regular occurrence.
The Philippines sits on the Pacific "Ring of Fire", where tectonic plates collide deep below the Earth's surface.
Schools in the region around Taal, some government offices in Manila and the Philippine Stock Exchange are closed as a precaution.
Dust masks sold out in stores as authorities warned locals that the ash could cause respiratory problems especially in the very young and those with pre-existing lung conditions.
Limited flight operations have resumed at Manila's main international airport, nearly a day after authorities halted them due to the safety risk volcanic ash poses to planes.
However, travellers booked on over 240 cancelled flights still faced delays at Ninoy Aquino International Airport.
The eruption began with an explosion of superheated steam and rock, but by early this morning "fountains" of lava had been spotted on Taal, the Philippine Institute of Volcanology and Seismology (Phivolcs) said.
Stunning lightning shows have periodically played out above the volcano in a little-understood phenomenon that is attributed to static electricity.
Authorities raised the volcano alert level to its second-highest, saying an "explosive eruption" could happen in "hours to days".
Phivolcs chief Renato Solidum told AFP the lava was evidence of fresh movement in the volcano, but said it was unclear if Taal would "sustain its activity".
Government seismologists recorded magma moving towards the crater of Taal, which is located 65km south of Manila.
Apart from the ash, some particles up to 6.4cm in diameter, larger than a golf ball, had reportedly fallen in areas around the lake, Phivolcs said.
Taal's last eruption was in 1977, Mr Solidum said.
Two years ago, Mount Mayon displaced tens of thousands of people after spewing millions of tonnes of ash, rocks and lava in the central Bicol region.
The most powerful explosion in recent years was the 1991 eruption of Mount Pinatubo, about 100km northwest of Manila, which killed more than 800 people.