Chinese government authorities on Thursday morning moved to shut off transportation in and out of Wuhan, the epicenter of the coronavirus outbreak that has killed 17 people and infected hundreds. Authorities put two more cities, Huanggang and Ezhou, under a travel ban later on Thursday. The three cities have a combined population of almost 20 million.
The dramatic attempt to contain the virus comes as Beijing tries to shake criticism that its cover-up of the 2002-2003 spread of the deadly SARS virus increased its death toll.
On Thursday morning, Chinese officials stopped planes and trains scheduled to leave Wuhan, blocked highways, and suspended public buses, subways, and ferries within the city.
As the city came to a standstill, Wuhan residents rushed to supermarkets and pharmacies and queued up for petrol.
“Nobody was ready for the lockdown,” one Wuhan resident told the South China Morning Post. “I went to the supermarket this morning, many people were there and vegetables were all sold out.”
As China moved to contain the spreading coronavirus outbreak, the World Health Organization (WHO) held an Emergency Committee meeting on Wednesday to discuss the situation, but delayed a decision on whether to declare a global public health emergency due to the “evolving and complex” nature of the situation.
The international health group is set to meet again on Thursday to decide on a health emergency declaration.
The spreading virus
Wuhan, the provincial capital of landlocked Hubei, has a population of 11 million people—over two million more than New York City—and is one of China’s most vital thoroughfares.
“This city happens to be a hub—a transportation hub and also a financial hub […] It’s the most important city in central China,” says Alfred Wu, an associate professor at the National University of Singapore who studies the political economy of Greater China.
Before the transportation lockdown, Wuhan’s role as a hub helped the virus spread. As of Thursday, the virus had sickened nearly 600 people and killed 17, many of whom had pre-existing health conditions. Cases have been confirmed in some of China’s biggest cities including the capital, Beijing, as well as Shenzhen, Hong Kong, and Macau.
The Centers for Disease Control (CDC) on Tuesday confirmed the first case of the Wuhan coronavirus in the U.S., from a patient who had recently traveled to the Chinese city. A total of 16 people who came into contact with the infected man are under observation in the U.S., and the CDC is developing a test for the virus to distribute to state health departments.
Officials in Japan and South Korea have reported one case each, and four cases have been confirmed in Thailand. The U.S. case is the first confirmed report of the virus outside of Asia.
Hong Kong SARS memories
Officials confirmed the first case of the Wuhan virus in Hong Kong on Wednesday, and announced a second case soon after. The first patient arrived from mainland China by train on Tuesday evening with signs of fever and told authorities he had been to Wuhan.
Even before the Hong Kong government announced the first case, a majority of pedestrians and public transport passengers in the city were already donning green and blue medical masks—this time to protect against infection rather than as a political signifier.
And for the past few weeks, Hong Kong’s subway stations have run loudspeaker announcements on loop, encouraging commuters to wash their hands with soap and wear masks if they have flu symptoms (cough, cold, fever, sore throat), and if they feel unwell, to alert station staff, who man “caring point” booths on some station platforms, wearing medical masks.
The 2002-2003 outbreak of severe acute respiratory syndrome, or SARS, remains vivid for many in Hong Kong. The city came to an effective standstill during the outbreak, which infected 1,755 and killed 299 in Hong Kong out of more than 800 fatalities worldwide.
The timing of the outbreak coincides with the start of China’s Lunar New Year public holiday, when people are expected to take three billion trips across the country, sparking fears of the disease spreading further.
Canceled journeys and drops in spending could wound China’s already-slowing economy: during last year’s holiday period, people spent an estimated $74 billion on travel and $145 billion on shopping and food.
A virus outbreak would also likely batter Hong Kong’s economy, which entered recession last year under strain from from months of anti-government protests that dented tourism and retail. The 2002 SARS outbreak pushed Hong Kong’s economy into recession in the first half of 2003.
This week, Hong Kong’s stock market recorded its worst day in more than five months amid mounting news of the coronavirus outbreak and a Moody’s credit rating downgrade.
Hong Kong-based Cathay Pacific Airways, which just suspended flights to Wuhan, is letting employees wear surgical masks and will allow passengers to and from Wuhan to cancel or change their flights for free through March 31. Between Dec. 2002 and April 2003, shares in Cathay Pacific dropped almost 30% due to the SARS crisis.
Governments and companies across Asia are taking serious precaution in the wake of the current virus outbreak.
Airport authorities across the Middle East, in Australia, and in other countries have instituted virus screening measures for arrivals. North Korea put a temporary ban on foreign tourists, many of which visit from neighboring China.
Large companies with operations in China, including HSBC Holdings, Citic Securities, and Chinese tech giant Tencent Holdings, restricted employee travel to Wuhan, and Singapore Airlines’ budget carrier Scoot suspended daily flights to Wuhan on Thursday.
More must-read stories from Fortune:
—The World’s Most Admired Companies in 2020
—A.I. in China: TikTok is just the beginning
—China braces for a deadly new virus as millions travel for Lunar New Year
—CEOs more pessimistic about global economy than they’ve been in 8 years
—U.S. brands think they understand China’s market, but they don’t
Catch up with Data Sheet, Fortune’s daily digest on the business of tech.