Mount Etna on the Italian island of Sicily has erupted.
A BBC team and some tourists were on the volcano when the explosion happened.
BBC science reporter Rebecca Morelle described the experience of "Running down a mountain pelted by rocks, dodging burning boulders and boiling steam" and says they had "a very narrow narrow escape".
The emergency services thankfully got everyone off the mountain safely with no serious injuries.
Rebecca Morelle said a volcanologist who was there at the time had told her it was the most dangerous incident he had experienced in his 30-year-career.
Lava flow mixed with steam had caused a huge explosion, which pelted the group with boiling rocks and steam, she said.
Mount Etna is one of the most active volcanoes in the world, it's been erupting for the last three weeks.
Mount Etna erupts a few times a year.