TAGAYTAY, Philippines — Red-hot lava spewed from a volcano near the Philippine capital of Manila on Monday as tens of thousands of people fled through heavy ash and frightening tremors, and authorities made plans to evacuate hundreds of thousands more for fear of a bigger eruption.

Clouds of ash from the Taal volcano reached Manila, 40 miles to the north, on Sunday, forcing the shutdown of the country’s main airport, with more than 500 flights canceled. The airport partially reopened Monday after the ashfall eased.

There were no immediate reports of any deaths or major damage directly blamed on the eruption.