Thousands of people were in emergency shelters in southwest Japan on Sunday as powerful Typhoon Nanmadol slammed into the region, prompting authorities to order nearly three million residents to evacuate.

The Japan Meteorological Agency (JMA) has issued a rare “special warning” for the Kagoshima region in southern Kyushu Prefecture — an alert that will only be issued if it predicts conditions that occur once in several decades.

As of Sunday morning, 25,680 households in Kagoshima and neighboring Miyazaki were already without power while regional train services, flights and ferry services were canceled pending the storm’s passage, local utilities and transportation services said.

The JMA has warned the region could face “unprecedented” danger from high winds, storm surges and torrential rain.

“Maximum caution is required,” Ryuta Kurora, head of the JMA’s forecasting unit, said on Saturday.

“It’s a very dangerous typhoon.”

“The wind will be so fierce that some houses may collapse,” Kurora told reporters, also warning of flooding and landslides.

So far, 2.9 million Kyushu residents have been warned about evacuation, according to the state Fire and Disaster Management Agency, and Kagoshima officials said over 8,500 people were already in local emergency shelters as of Sunday morning.

The evacuation warnings are urging people to seek shelter or alternative housing that can withstand extreme weather.

But they’re not mandatory, and during past extreme weather events, authorities have struggled to persuade residents to seek shelter quickly enough.

Kurora urged people to evacuate before the worst of the storm hit, warning that residents must take precautions even in sturdy buildings.

“Please move into stable buildings before strong winds start blowing and stay away from windows even inside stable buildings,” he told a late-night news conference.

As of Sunday morning, high-speed train operations in the area were suspended along with regional rail lines, and NHK said at least 510 flights had been cancelled.

“The southern part of the Kyushu region may experience fierce winds, high waves and floods that have never been experienced before,” the JMA said on Sunday, urging residents “to exercise the utmost caution.”

At the scene, a Kagoshima Prefectural official told AFP there had been no reports of injuries or structural damage, but that conditions were getting worse.

“The rain and the wind are getting stronger. The rain is so heavy you can’t really see what’s out there. It looks all white,” he said.

At 9:00 a.m. (0000 GMT), the typhoon was 80 kilometers (50 miles) southeast of the Japanese island of Yakushima, packing gusts of up to 252 kilometers per hour.

It is expected to land in Kyushu on Sunday evening before turning northeast and sweeping across Japan’s main island until early Wednesday.

Japan is currently in typhoon season and faces about 20 such storms a year, with regular heavy rains causing landslides or flash floods.

In 2019, Typhoon Hagibis slammed into Japan while it was hosting the Rugby World Cup, claiming the lives of more than 100 people.

A year earlier, Typhoon Jebi paralyzed Osaka’s Kansai Airport, killing 14 people.

And in 2018, floods and landslides killed more than 200 people during the country’s annual rainy season in western Japan.

Scientists say climate change is increasing the severity of storms and making extreme weather events like heat waves, droughts and flash floods more frequent and intense.