Mount Sinabung on Sumatra, Indonesia is at the highest alert level as it spewed smoke and hot ash that flowed up to 2.5 kilometers (1.5 miles) from its mouth to the slope, AP reported.

Government volcanologist Surono urged villagers to stay out of the main danger zone that reaches about 7 kilometers (4 miles) to the southeast of the crater. 

"The growing size of the lava dome is very unstable," said Surono, who goes by one name. He also warned that smoldering rocks combined with hot gases may also tumble down the volcano at any moment.

Thick smoke and ash were seen at more than 500 meters (1,640 feet) in the air since Monday, CNN News reported. It also had more than 50 eruptions on Wednesday with volcanic lava flowing from its mouth, prompting the villagers to evacuate to a safer place immediately.

More than 2,700 people left their villages that are near the crater and moved into several temporary shelters that are free from danger.

According to Volcano Discovery, the alert level of the volcano was raised from "siaga" to "awas," which is the highest on the Indonesian scale of 1-4.  

Mount Sinabung is located on the Pacific Ring of Fire and is among the 130 active volcanoes in Indonesia.

The 2,600-meter (8,530-foot) volcano in North Sumatra has had isolated eruptions since 2010 and remained dormant for 400 years. 

Last year, said volcano erupted, killing 17 people.