Nicaraguan authorities are using army forces to evacuate people from the base of the San Cristobal volcano after it began to erupt Tuesday night.

The authorities declared an “amber alert” for a 2 square mile area around the volcano warning of the risk of major eruption. Airlines were also told to avoid flying over the western part of the country due to ash plumes.

Ash and hot gases from the top of the mountain reached over a mile and a half into the sky. Scientists report that ash could fall over 11 cities near the volcano before the current eruption is over.

However, the eruptions have been classified as “small” and said a larger one could create a greater risk to the population and farms in the area.

San Cristobal is the highest volcano in Nicaragua.