Glowing red lava is flowing down the Philippines’ most active volcano, causing 21,000 villagers to flee and prompting police to set up checkpoints to prevent tourists from getting too close.

The Philippine Institute of Volcanology and Seismology said the lava flowed as much as 1.2 miles from the crater of Mount Mayon on Tuesday, while ash fell on several villages in the north-eastern Albay province.

Officials strongly advised people not to venture into a danger zone with a radius of about three to four miles around Mayon. There are concerns over residents who want to check their homes, farms and animals – and tourists who are seeking a closer view.