Residents are being taken to safe areas away from the Philippines' second-most active volcano, Taal.
Authorities Friday continued their efforts to remove people from homes after the volcano spewed steam and ash more than a kilometer into the sky late Thursday.
The eruption led officials to raise the alert level for people living nearby. Experts said magmatic material had come into contact with water in the main crater, causing the steam. The Philippine Institute of Volcanology and Seismology posted a video on social media of the lake in Taal's crater, which appeared to have boiled - an event known as a phreatomagmatic eruption.
"Phreatomagmatic is more dangerous because there's already an interaction with magma," Maria Antonia Bornas, chief of the agency's monitoring and eruption prediction division, said.
Officials said the steam-driven blast was not accompanied by a volcanic earthquake, which is a good sign. However, no one is taking any risks as the incident could lead to a full-blown eruption.
Phivolcs said it had already raised the alert level to the third in its five-level warning system. An alert level at the highest end of the warning system indicates an imminent eruption that could endanger the lives of all people living within the immediate vicinity.
The Taal Volcano, which looks like an island situated within Taal Lake, is a volcanic caldera formed more than 500,000 years ago. Last year, an eruption had displaced hundreds of thousands of people. The eruption sent ashes as far as the capital Manila, more than 65 kilometers away.
The Philippine government's disaster-response agency said it has already warned residents to stay away from the small island where the volcano is located. The agency said at least 3,500 families composed of 14,495 individuals have been forced to temporarily relocate.
Phivolcs chief, Renato Solidum, said this year's eruption isn't as bad as last year's.
"The explosion stopped after five minutes and it's possible that the unrest could be just that or it can escalate. But, so far, we are not seeing anything unusual with the volcano's swelling," Solidum said.
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