An Indonesian volcano that has been dormant for hundreds of years erupted for a second straight day on Monday, forcing thousands of people out of their homes.

Mount Sinabung in North Sumatra has long been considered inactive because it last erupted more than 400 years ago.

It erupted for the first time over the weekend and erupted again early Monday, spewing clouds of soot and ash into the air, the Indonesian meteorology agency said.

As many as 30,000 people who live near the mountain have fled their homes, freelance journalist Michel Maas reported.

Maas said villagers living along the slopes have packed their belongings and headed to emergency shelters, mosques and churches.

Health officials have been distributing thousands of face masks to help people protect themselves from the ash and smoke billowing into the air.

While two people have died — a 64-year-old woman from respiratory problems and a 52-year-old man from a heart attack — it was too early to say if the volcano was to blame, said Priyadi Kardono of the National Disaster Management Agency.

Sinabung last erupted in 1600, so observers don't know its eruption pattern and admitted over the weekend that they had not been monitoring it closely before it started rumbling days ago in the lead-up to Sunday's first, less-powerful blast.