WATCH: Italy's Mount Etna Erupts, Tourists Flee

Mount Etna, the rambunctious volcano on the Italian island of Sicily, grumbled back to life on Monday, spewing hot ash and lava in a pyroclastic flow, the nation's volcano monitoring body said. There were no reports of any risk to the local population, which is accustomed to Etna's frequent eruptions, or to air travel.

The volcano department, which is run by Italy's National Institute of Geophysics and Vulcanology, noted on Monday "explosions of increasing intensity" that it said were "almost continuous."

By noon local time, INGV Vulcani said in a social media post that the "explosive activity from the Southeast Crater has become a lava fountain," and infrared images posted by the group showed the flow of lava down the mountain's face.

Video shared earlier on the institute's Facebook page showed a massive plume of smoke and ash rising into the clear blue sky.

The volcano department said the eruption was caused by part of Etna's southeast crater collapsing, which released the lava flows.

The only danger was in the area right around the summit of Etna, which was blocked off to tour groups on Monday as a precaution, The Associated Press quoted INGV official Stefano Branca as saying. One video posted on social media showed tourists who had been on Etna running along a path on the side of the volcano as smoke billowed in the distance behind them.

The AP cited Renato Schifani, the head of Sicily's regional government, as saying the pyroclastic flows "posed no danger to the population" of the island.

Mount Etna is considered the most active volcano in Europe, and the most active stratovolcano in the world. A stratovolcano — what many people think of when they hear the word volcano — is the conical type, often with a central crater, that is formed by layer upon layer of lava from repeated eruptions over the millennia.

Etna had a significant eruption just over a year ago, when it treated watchers to rare ring-like clouds puffed out by its crater, known as vortex bubbles.

Etna has erupted at least once every year for the past several years, sometimes covering nearby towns in a layer of volcanic dust, but causing no major problems otherwise.