New Delhi, Sept. 1 -- Mount Sinabung on Indonesia erupted Monday, spewing a column of black ash and smoke 3,500 meters (11,482 feet) from the top of the mountain into the sky over Sumatra island.

There were no immediate reports of casualties, evacuations or disruptions to flights in the region. But residents, visitors and tourists were advised to refrain from activities in nearby villages in Karo district in North Sumatra province and areas within 6 kilometers (3.7 miles) of the summit.

Roads, vehicles and buildings in several villages in Karo affected by the eruption were covered in gray ash. Local authorities distributed masks to residents to protect themselves.

Officials raised the volcano alert level to "Watch," the second-highest ...