Etna is the largest and most active volcano in Europe. It has been erupting over the past couple weeks, but Thursday's explosive event was unexpected. The phreatic eruption was caused by the melting of snow cover, which almost instantaneously turned to steam and caused the large explosion.
One volcanologist on the scene said it was the most dangerous event he's seen in 30 years of experience. BBC science correspondent Rebecca Morelle recounted the incident to the BBC and fired off a series of tweets outlining the situation, the danger, and ultimately how lucky the team had been to escape serious injury, in part thanks to an "excellent" rescue team, according to Morelle.