Papua New Guinea’s volatile Ulawun volcano — designated one of the world’s most hazardous — erupted Wednesday, spewing lava high in the air and sending residents fleeing.

A pilot for Niugini Helicopters flying near the crater witnessed a column of lava spurting vertically into the equatorial sky, along with ash that has been belching since early morning.

Ulawun, on the remote Bismarck Archipelago chain, is listed as one of 16 “Decade Volcanoes” targeted for research because they pose a significant risk of large, violent eruptions.