Indonesia’s Anak Krakatau volcano erupted on Saturday, sending plumes of volcanic ash into the sky over the Sunda Strait between Java and Sumatra, while authorities urged residents, tourists and visitors to stay away from the volcano, Reuters reported.

The eruption began at 11.07 pm local time on Friday and continued through the observation period from midnight to 6am on Saturday, according to Indonesia’s National Disaster Mitigation Agency (BNPB), citing monitoring by the Centre for Volcanology and Geological Hazard Mitigation (PVMBG).

Stefan Burns said the ash plume is 15-20 km into the sky.