Sicily’s tallest volcano, Mount Etna erupted Thursday, after about two years of inactivity. The volcano, located in Southern Italy turned the cloudless sky bright red, as it erupted in the early morning hours.

The eruption was one of the most violent eruptions in decades, according to scientists. Ash was launched 10,000 feet into the sky by the explosion inside Mount Etna’s crater. According to Italy’s National Institute of Volcanology, the eruption for continued for about an hour. The lava shot about a mile into the air, The Washington Post reports.

Winds carried ash from Mount Etna into Sicilian villages, as seen on satellite images. Lightning was spotted inside the ash cloud emitted from the volcano. In intense volcanic eruptions, lightning occurs in a similar manner to that in thunderstorms.

In thunderstorms, positive and negative charges separate from one another in the atmosphere, while lightening serves to balance that separation. In a volcanic eruption, researchers do not completely understand why a charge separation occurs. Some suggest that the ash contains an electrical charge that interacts with the atmospheric charge in the air.

Volcanic lightning exclusively occurs in the most intense eruptions, and is nearly impossible to capture. The lightning typically only occurs at the beginning of an eruption. The lightning is at one of the hottest temperatures on Earth, at around 50,000 degrees Fahrenheit, considerably warmer than the temperature of the lava erupting from the volcano.