(CNN) Bali residents living next to a smoldering volcano are being urged to evacuate as soon as possible, amid warnings from emergency agencies of another larger eruption.

Almost 30,000 people have already left the area around Mount Agung since it began erupting on Saturday, spewing clouds of ash reaching as high as 9,100 meters (at least 5.6 miles).

Indonesia's National Board for Disaster Management (BNPB) said on social media up to 100,000 locals living in the danger zone needed to evacuate urgently but rescuers were facing resistance.

"Not all villagers in the dangerous radius are willing to evacuate. Until now there are still many people who remain in their houses," the disaster agency said, adding some were staying behind to protect gardens and livestock.

Clouds of smoke continued to pour from the crater Tuesday morning, with authorities remaining on the highest alert level possible in anticipation of another, larger eruption.

Spokesman for the BNPB Sutopo Purwo Nugroho said there was growing seismic activity around Mount Agung, indicated another eruption could occur soon.

Photos: Indonesia's Mount Agung volcano erupts Clouds of ashes rise from the Mount Agung volcano erupting in Karangasem, Bali, Indonesia, Tuesday, November 28. The volcano erupted for the first time in more than half a century, forcing closure of the Indonesian tourist island's busy airport and forcing tens of thousands from their homes. Hide Caption 1 of 14 Photos: Indonesia's Mount Agung volcano erupts Passengers gather at the Ngurah Rai International Airport in Denpasar, Bali, on November 28, 2017, to wait for possible flights out after the Mount Agung volcano eruption. Hide Caption 2 of 14 Photos: Indonesia's Mount Agung volcano erupts An elementary school student wears a face mask on school grounds before school in Karangasem, Bali, Indonesia, on November 28. Hide Caption 3 of 14 Photos: Indonesia's Mount Agung volcano erupts Smoke and ash is lit from within Mount Agung on November 28. Hide Caption 4 of 14 Photos: Indonesia's Mount Agung volcano erupts Evacuees fill an emergency shelter in Klungkung, Bali, Indonesia, on Monday, November 27 Hide Caption 5 of 14 Photos: Indonesia's Mount Agung volcano erupts People gather to look at ash and debris from the eruption on the river Yeh Sah on November 27, in Bali, Indonesia. Hide Caption 6 of 14 Photos: Indonesia's Mount Agung volcano erupts A villager takes his cows to a field with Mount Agung volcano seen in the background near Karangasem, Bali, Indonesia, on Tuesday, Novenber 28. The eruption has forced tens of thousands of people to evacuate their homes. Hide Caption 7 of 14 Photos: Indonesia's Mount Agung volcano erupts Ash and debris erupt from Mount Agung on November 28.Thick ash started shooting thousands of meters into the air above Mount Agung on Saturday, November 25. Hide Caption 8 of 14 Photos: Indonesia's Mount Agung volcano erupts Students stand on a truck on their way to go to school, with erupting Mount Agung in the distance. The National Agency for Disaster Management issued a Level 4 alert on Monday, November 27, indicating the potential for another larger eruption and recommending no public activities within 8 to 10 kilometers from the peak of the volcano. Hide Caption 9 of 14 Photos: Indonesia's Mount Agung volcano erupts Passengers gather at the Gusti Ngurah Rai International airport in Denpasar, Bali on Monday, November 27, after flights were canceled because of ash from erupting Mount Agung volcano. Hide Caption 10 of 14 Photos: Indonesia's Mount Agung volcano erupts Volcanic material from the eruption flows through a local river in Gesing Villageon November 27, while villagers watch nearby ,in Karangasem, Bali, Indonesia. Hide Caption 11 of 14 Photos: Indonesia's Mount Agung volcano erupts Residents at Gesing village are seen sitting in front of a sign restricting entry to the area on November 27, in Karangasem, Bali, Indonesia. Hide Caption 12 of 14 Photos: Indonesia's Mount Agung volcano erupts Evacuees unload building materials for temporary shelters at Rendang Evacuation Center on November 27, in Karangasem, Bali, Indonesia. Hide Caption 13 of 14 Photos: Indonesia's Mount Agung volcano erupts Mount Agung spews volcanic ash into the night sky on November 27, near Karangasem, Bali, Indonesia. Hide Caption 14 of 14

"rays of fire" were increasingly observed in the volcano's crater, according to a Facebook post by the Over Monday night,"rays of fire" were increasingly observed in the volcano's crater, according to a Facebook post by the BNPB, while another post on Tuesday warned of "increasing volcanic activity."

"Mount Agung eruption keeps going ... The possibility that the bigger eruption might happen (is getting) closer. However there is no clear information on how big the intensity (would be). It is nearly impossible to estimate," the disaster agency said.

The BNPB maintained a Level 4 alert on Tuesday, mandating no public activities within 10 kilometers of the peak.

On Monday evening, a red level aviation warning was reissued by Indonesia's Center for Volcanology and Geological Hazard Mitigation due to the ongoing eruption.

Arie Ahsanurrohim, spokesman for Bali's largest airport, Ngurah Rai, announced early Tuesday morning flights would be grounded for another day over fears of volcanic ash.

All flights out of the airport are grounded until 7 a.m. local time Wednesday. More than 50,000 domestic and international passengers have already been stranded by the eruption.

A fisherman drives a traditional boat as Mount Agung erupts in Bali on November 28.

The BNPB said there would be a re-evaluation of the decision to keep airports closed every six hours.

Bali is a popular tourist destination in eastern Indonesia which sees more than a million visitors from Australia every year, as well as hundreds of thousands from around the region, including China.

The main tourist centers are some distance from Mount Agung. Bali's artistic hub, the small town of Ubud, is about 50 kilometers (31 miles) southwest of the volcano, and Denpasar (where the airport is located) and the popular Kuta Beach are more than 63 kilometers (40 miles) away.

Tourists spoke to CNN of the travel chaos caused by the volcano, with some unable to leave Bali for three days.

Ash began spewing from Agung after it erupted three times on Saturday, beginning at around 5.30 p.m. local time. More eruptions followed on Sunday, with a "medium-pressure" event in the early evening.