Authorities have issued the highest-level warning possible after volcanic eruptions from Mount Agung on the Indonesian resort island of Bali forced the closure of the island’s main airport and evacuation of thousands of residents living nearby.

Thick ash started shooting thousands of meters into the air above Mount Agung on Saturday, driving east and southeast along the archipelago, forcing more than 29,000 people to evacuate from their homes, the Bali Provincial Board for Disaster Relief said, revising their initial estimate.

At Ngurah Rai International Airport, Bali’s main airport, flights were canceled for 24 hours from 7:15 a.m. Monday local time (6 p.m. Sunday ET), stranding roughly 59,000 domestic and international passengers, according to the airport’s latest report.

“While the sun is shining and there is little sign of volcanic ash in the southern regions of Bali, evidence of volcanic ash at higher altitudes on aviation approach and departure paths has prompted the decision to close the airport,” Bali Tourism Board Chairman Ida Bagus Agung Partha Adnyana said in a statement.

The National Agency for Disaster Management issued a Level 4 alert on Monday, indicating the potential for another larger eruption and recommending no public activities within 8 to 10 kilometers from the peak.

Anyone within that distance of the peak was advised to evacuate.

On Sunday, Indonesia’s Center for Volcanology and Geological Hazard Mitigation raised its aviation alert notice to Red, the highest level.

Regular rain in the area around the volcano has created a series of volcanic mud flows, Sutopo Purwo Nugroho, head of information and data for Indonesia’s National Disaster Management Agency said.

“The pyroclastic material of (the) Mount Agung eruption will continue to grow. The rain will increase during the rainy season. Potential lava floods will increase. Do not do (engage in) activities around the river,” he said on his official Twitter.

Lombok International Airport on Lombok, the island due east of Bali, closed temporarily, said Ari Ahsan, spokesman for Ngurah Rai airport. Flights from Lombok resumed early Monday.

‘Amazing and scary’

Bali is a popular tourist destination which welcomes more than a million visitors from nearby Australia every year, as well as hundreds of thousands of Chinese guests.

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.

Freelance writer Ann Goryainova, 34, said she was traveling on Lombok when Agung finally erupted.

“(I can) see a huge steam and ash cloud over the volcano from here, amazing and scary at the same time,” she told CNN, while adding there was no panic on the island around her.

Actor Derek Du Chesne, 30, said he was having a very difficult time trying to find a flight home to the United States.

“The last two days we couldn’t get out of here. Traffic gridlocked, buses lining the streets for evacuation. We couldn’t get through to any of the airlines via phone, been on hold for an hour now, scary stuff,” he said.

Tens of thousands of people were evacuated from their homes around Mount Agung in September when the alert was first raised. At the time, an evacuation zone of 12 kilometers around Mount Agung was established, and travelers were warned to stay clear of the area.

The evacuation zone is based on the last time Agung erupted in 1963, killing more than 1,700 people and destroying many villages, some on the slopes of the mountain.

Eruptions started Saturday

The ash, which began spewing into the sky after Mount Agung in eastern Bali erupted three times Saturday, has reached heights of 4,000 meters (about 2.5 miles), according to Sutopo.

According to Australia’s Bureau of Meteorology, by Monday morning the continuous cloud of smoke had reached as high as 9,100 meters (at least 5.6 miles).

The first eruption came around 5:30 p.m. Saturday, Bali’s Regional Disaster Management Agency said. More eruptions followed and continued into Sunday, with a “medium-pressure eruption” in the early evening.

“The volcanic eruption has now moved on to the next, more severe, magmatic eruption phase, where highly viscous lava can trap gasses under pressure, potentially leading to an explosion,” Mark Tingay, a geologist at the University of Adelaide’s Australian School of Petroleum, said in a statement Monday.

“The local authorities are extremely experienced in managing volcanic eruptions, and have the situation extremely well in-hand.”

Ash fall was reported in the villages of North Duda, East Duda, Pempetan, Besakih, Sidemen, Tirta Abang, Sebudi, Bhuana Amerta in Klungkung and in some villages in Gianyar. Masks are being distributed in Bali and Pulau Lombok.