A huge and powerful typhoon is headed toward southern China after lashing the Philippines with destructive winds and torrential rain, putting the region’s megacities on high alert with cancelled flights and disruptions to schools and businesses.

Axar.az informs, citing CNN, tens of millions of people could be impacted by the storm, which is expected to pass south of the major cities of Hong Kong, Macau, Shenzhen and Guangzhou, before making landfall again in mainland China’s Guangdong Province.

Typhoon Ragasa hit the northern Philippines as the strongest storm on earth so far this year, after generating sustained winds of over 267 kph, the equivalent of a Category 5 hurricane.

Authorities in China have activated emergency responses. Entire megacities in Guangdong, one of the world’s most populous regions, have been brought to a standstill ahead of the storm, with schools closed and work suspended, some businesses shut, and public transport halted.

Guangzhou, a city of 18.6 million people, may issue its highest red alert on Tuesday, while in Shenzhen, home to about 17.5 million residents, officials were preparing to relocate 400,000 people from low-lying and coastal areas.

Hundreds of flights have been disrupted across the region, with cancelations in Taiwan, Hong Kong and southern China. Hong Kong-based airline Cathay Pacific said it will stop passenger flights scheduled to leave and arrive in the city on Tuesday evening until Thursday morning. Hong Kong Airlines, another regional carrier, also suspended dozens of flights for the week.