Magma hit the snow, causing an explosion of debris that pelted bystanders as they raced for safety, injuring at least 10, reported the Associated Press.
Six members of a BBC team of journalists were among the injured Thursday after Mount Etna, a volcano in Sicily, began to erupt, sending boiling hot rocks flying into the air.
The last aggressive eruption was in 1928, which destroyed the town of Mascali.
The violent explosion caught the crew unawares while they were filming a report on the volcano.
Mount Etna has been putting on an impressive show for days, spewing lava and steam.
Marino told Catania Today, "The material thrown into the air fell back down, striking the heads and bodies of people who were closest".More news: Scotland Wants Another Vote for Independence Before Brexit
The eruption happened at about 11:30am on Thursday and left nearly a dozen injured.
The president of the Italian Alpine Club chapter in Catania, Umberto Marino, was travelling up the volcano when injured people started running in his direction.
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.
Europe's largest and most-active volcano suddenly erupted Thursday. But no one expected the explosion that sent ash, rocks and steam toward sightseers at temperatures of over 1,800 degrees. "Volcanologist said most risky incident experience in his 30 year career", Morelle tweeted.
Italy's Mount Etna has consistently erupted for thousands of years, as shown in this picture from October 30, 2002.