Wuhan, a Chinese city of nearly nine million people, is to temporarily shut public transport amid a virus outbreak.
Those living in the city have been advised not to leave, in a week when millions of Chinese are travelling for the upcoming Lunar New Year holiday.The airport and train stations will be closed to outgoing passengers.
Bus, subway, ferry, and long-distance transport networks will shut down from 1000 local time on 23 January.
Those living in the city had already been told to avoid crowds and minimise public gatherings.
The outbreak has killed 17 people, and there are more than 500 confirmed cases.
The virus originated in a seafood market that "conducted illegal transactions of wild animals", authorities said.
It has spread from Wuhan to several Chinese provinces, the US, Thailand and South Korea.Late on Wednesday, Chinese authorities confirmed the number of dead had almost doubled - from nine - in the space of a day. All fatalities so far have been in Hubei, the province around Wuhan.
Officials in Hong Kong also reported the territory's first two cases.
Known as 2019-nCoV, the virus is understood to be a new strain of coronavirus not previously been identified in humans. The Sars virus that killed nearly 800 people globally in the early 2000s was also a coronavirus.
Meanwhile, in Geneva, the World Health Organisation's emergency committee is meeting to assess the global risks posed by the virus and decide if it should be declared an international public health emergency - as happened with swine flu and Ebola.
Chinese officials said the country was now at the "most critical stage" of prevention and control.
"Basically, do not go to Wuhan. And those in Wuhan please do not leave the city," said National Health Commission vice-minister Li Bin in one of the first public briefings since the beginning of the outbreak.
Earlier this week, China confirmed that human-to-human transmission of the virus had taken place.
Signs of infection with the new virus include respiratory symptoms, fever, cough, shortness of breath and breathing difficulties.
The first US case was confirmed on Tuesday. President Donald Trump said the situation was "totally under control" and that he trusted the information being provided by Chinese authorities.
Wuhan is starting to look like a city in quarantine.
Officials had already warned residents not to leave the city and visitors not to come.
Now the reported public transport ban - which includes flights - slams many of the routes in and out of the city shut.
It is a significant attempt to stop the spread of this new virus, which we now know can spread from person to person.
Limiting transport will cut the chance of the virus reaching other cities in China and other countries around the world.
This all comes just as millions of people are travelling across China for the week-long holiday that is Lunar New Year.
If you're struggling for context - imaging shutting down London in the week before Christmas.
The big question left is the roads - and whether any of Wuhan's 8.9 million inhabitants will be able to simply drive away.