Lockdown measures are increasing across China's Hubei province to try to control the spread of a new virus that has left 18 people dead in the country.
Wuhan, Hubei's capital of 11 million people where the virus first emerged, has no trains or planes in or out.
At least five other provincial cities are seeing clampdowns on transport.
There are more than 500 confirmed cases of the virus, which has spread abroad, with Singapore and Vietnam the latest affected.
The new strain of coronavirus is believed to have originated at a market in Wuhan. One resident of the city said the atmosphere there felt like "the end of the world".
The lockdowns come as millions of Chinese people travel across the country for the Lunar New Year holiday.
What's the latest in China?
All the fatalities bar one so far have been in Hubei province. Most of the 17 victims there were elderly and suffered from other chronic diseases including Parkinson's disease and diabetes.
An 18th victim, an elderly patient, was announced on Thursday in Hebei province, near the capital, Beijing.
Wuhan's public transport lockdown came into force as of 10:00 local time (02:00 GMT), leaving normally busy train stations and airports empty.
One Wuhan resident said on social media site Weibo that people were on the "verge of tears" when they heard about the closures.
Health authorities are reported to have made wearing a mask mandatory in the city. They are advising people to avoid crowds and public gatherings.
Demand for rubber gloves and surgical masks has soared. Taobao, the Chinese online retail giant, has warned sellers not to profit from the outbreak by raising prices.
Also in Hubei province:
- Huanggang, a city east of Wuhan, suspended bus and rail services and encouraged people not to leave the city. Cafes, cinemas, theatres and exhibitions are also being shut
- Ezhou, just south of Huanggang, has shut its train stations
- Xiantao has cancelled gatherings, suspended transport and set up temperature detection stations
- Chibi and Lichuan are suspending transport, AFP news agency reports
Beijing announced it had cancelled all major Chinese New Year celebrations.
A doctor at a hospital in Wuhan spoke to the BBC
The virus is now spreading at an alarming rate. The hospitals have been flooding with thousands of patients, who wait hours to see a doctor. You can imagine their panic.
Normally Wuhan is a great place to live and we are proud of our work. Specialists here have developed a guide for coronavirus diagnosis and treatment.
But I am scared because this is a new virus and the figures are worrying.
Two days ago we were told not to go to work because of the risk of contamination. If we leave our home on the hospital campus, we are required to wear masks.
We don't want to take our two-year-old son outside. He's sleeping now, and we are trying to protect him as much as possible: handwashing, airing the apartment, avoiding contact with people.
Outside I can barely see anyone on the streets. We have been told to avoid gatherings.
I went to the supermarket to buy food, but there was nothing left, no vegetables or biscuits. Some Lunar New Year celebrations are cancelled.
People had bought tickets to go home for Lunar New Year but they can't go now. Everyone is stuck here and can't leave.
What do we know about the virus?
Currently known as 2019-nCoV, the virus is understood to be a new strain of coronavirus not previously identified in humans. The Sars (Severe Acute Respiratory Syndrome) virus that killed nearly 800 people globally in the early 2000s was also a coronavirus, as is the common cold.
Authorities have said this new virus originated in a seafood market in Wuhan that "conducted illegal transactions of wild animals". The market has been shut down since the beginning of the year.
There is evidence of human-to-human transmission, with the virus spreading from patients to family members and healthcare workers.
But understanding more about how the virus transmits between people is one of the major outstanding questions.
The virus infects the lungs, and symptoms start with a fever and cough. It can progress to shortness of breath and breathing difficulties.
What's the picture globally?
The World Health Organization (WHO) emergency committee said on Thursday that it was not the time to declare an "international emergency" over the new virus, although it was "an emergency in China".
Its 16-member experts' panel was divided 50-50 on the issue, the WHO said, but had decided overall that it was too early because of the limited number of cases abroad, the efforts made by China to control the virus and the fact there was no evidence of human-to-human transmission outside of China.
A global emergency is the highest level of alarm the WHO can sound, and has previously been used in response to swine flu, Zika virus and Ebola.
Authorities around the world have announced screening measures for passengers from China.
Thailand has confirmed four cases of the virus, the most outside China. The US, Japan, Taiwan, South Korea have all reported one case each.
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
On Thursday, two more nations confirmed cases:
- Singapore, where a 66-year-old man who had travelled from Wuhan is being held in an isolation room, and there is also another suspected case
- Vietnam, where the health ministry has confirmed two Chinese citizens in the country have the virus
An earlier report that an Indian nurse working in the city of Khamis Mushait in Saudi Arabia had tested positive was altered by the Indian consulate in Jeddah. It said the nurse was suffering from Mers-CoV, also a coronavirus.
Learn more about the new virus
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