On March 11, 1669, Mount Etna, on the island of Sicily in modern-day Italy, begins rumbling. Multiple eruptions over the next few weeks killed more than 20,000 people and left thousands more homeless. Most of the victims could have saved themselves by fleeing, but stayed, in a vain attempt to save their city.

Mount Etna dominates the island of Sicily. Rising 11,000 feet above sea level in the northeast section of Sicily, it can be seen from just about every part of the island. The geologic history of Mount Etna demonstrates that it has been periodically spewing ash and lava for thousands of years; the first recorded eruption of the volcano was in 475 BCE. It is the most active volcano in Europe. In 1169, an earthquake just prior to an eruption killed 15,000 people on Sicily. Despite the dangers of living near an active volcano, the eruptions made the surrounding soil very fertile, so many small villages developed on the slopes of the mountain.

When Etna began to rumble and belch gas on March 8, the residents nearby ignored the warning signs of a larger eruption. Three days later, the volcano began spewing out noxious fumes in large quantities. Approximately 3,000 people living on the slopes of the mountain died from asphyxiation. Even worse, Etna was soon emitting tremendous amounts of ash and molten lava. The ash was sent out with such force that significant amounts came down in the southern part of mainland Italy, in some cases nearly 100 miles away. Lava also began pouring down the south side of the mountain heading toward the city of Catania, 18 miles to the south along the sea.

At the time, the city of Catania had about 20,000 residents; most failed to flee the city immediately. Instead, Diego de Pappalardo, a resident of the city, led a team of 50 men to Mount Etna, where they attempted to divert the lava flow. Wearing cowhides soaked in water, the men bravely approached the lava with long iron rods, picks and shovels. They were able to hack open a hole in the hardened lava wall that had developed on the outside of the lava flow and much of the flow began to flow west out of the new hole. However, the residents of Paterno, a city lying southwest of Etna were monitoring these developments and quickly realized that this new flow direction could imperil their own city. They literally fought back the Catanians, while the lava breach hardened and filled again.

For several weeks, the lava pushed toward Catania and the sea. Still, the residents failed to evacuate the city. Apparently, they remained hopeful that the lava would stop or the city’s ancient defensive walls would protect them. Neither was the case—the walls were quickly swallowed by the extremely hot lava and nearly 17,000 people in Catania died. Most of the city was destroyed. Catania was not the only city affected—the eruption wiped out 14 towns and villages and left about 27,000 people homeless.

Following this disaster, it was decreed that interference with the natural flow of lava was prohibited in Italy, a regulation that remained in effect hundreds of years later.