Ten people were reported injured when the highly volatile volcano erupted and spewed clusters of the volcanic rock onto those below.
BBC global science reporter Rebecca Morelle was on hand for the event and said the Mount Etna explosion is "a reminder of how risky and unpredictable volcanoes can be" adding "everyone had a very lucky escape".
Etna rises above the town of Catania, and records of its activity date back to 1,500 B.C. According to the Volcano Discovery site, there have been more than four dozen eruptions, with one ongoing.
The blast is what's known as a "phreatomagmatic eruption", and is caused by extremely hot lava hitting much colder snow.
Among those present on the mountain at the time of the midday explosion was the BBC's global science reporter, Rebecca Morelle, who described the experience in a series of tweets.
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One scientist said it's the most risky incident he'd ever seen in 30 years of studying volcanoes.
The lava had mixed with some snow, causing a small explosion and then a larger one.
One volcanologist told the BBC that this latest eruption from Etna, one of the most active volcanoes on the planet, was the most unsafe he had seen in 30 years.
"Running down a mountain pelted by rocks, dodging burning boulders and boiling steam - not an experience I ever ever want to repeat", she wrote on Twitter.
Six people are recovering in the nearby Catania and Acireale hospitals, Il Corriere reports. Those injured suffered head injuries cuts, burns and bruises.