Thousands of people sought refuge in emergency shelters in southwestern Japan on Sunday as powerful Typhoon Nanmadol slammed into the region, prompting authorities to order over four million residents to evacuate.

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

Heavy rain and high winds lashed the area of ??Japan’s South Island on Sunday morning, with nearly 98,000 homes in Kagoshima, Kumamoto, Nagasaki and Miyazaki already without power.

Trains, flights and ferry services have been canceled pending the storm’s passage, and even some convenience stores – which are generally open 24 hours a day and are considered a lifeline during disasters – closed their doors.

“Please stay away from dangerous places and please evacuate if you feel even the slightest hint of danger,” Prime Minister Fumio Kishida tweeted after calling a government meeting on the storm.

“It will be dangerous to evacuate at night. Please go to safety while it’s still light outside,” he added.

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.

National broadcaster NHK, which collects local alerts, said more than four million people across Kyushu have been issued evacuation warnings, with officials in Kagoshima and Miyazaki saying over 15,000 people were in local emergency shelters as of Sunday afternoon.

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.

Bullet train operations in the area were suspended on Sunday morning and NHK said hundreds of 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.”

On the ground, an official in the town of Izumi in Kagoshima said conditions were rapidly deteriorating.

“The wind has become extremely strong. It’s also raining heavily,” he told AFP. “It’s totally white outside. Visibility is almost zero.”

On the shore of the city of Minamata, Kyushu, fishing boats moored for safety rocked on the waves as sea spray and streaks of rain swept the promenade.

As of 1 p.m. (0400 GMT), the typhoon was over the tiny island of Yakushima, packing gusts of up to 234 kilometers (146 miles) 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.