The Wuhan Pneumonia City-level Prevention and Control Headquarters issued a city closure announcement in the early morning, stating:
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From 10:00 on January 23, 2020, the city's urban buses, subways, ferries, and long-distance passenger transportation will be suspended; citizens should not leave Wuhan without special reasons, and the airport and railway station will be temporarily closed. "
Source: [Announcement of Wuhan New Coronavirus Pneumonia Epidemic Prevention and Control Headquarters] (https://www.thepaper.cn/newsDetail_forward_5605862)
A large number of citizens left Wuhan by road, railway, and civil aviation, and even those with symptoms publicly released information about escaping. At the same time, it can be judged that a considerable number of people have obtained information about the city closure in advance
Source Hong Kong Headline Daily: [Citizens fled the train station in the early morning before closing down the city] (https://hd.stheadline.com/news/realtime/chi/1686804/%E5%8D%B3%E6%99%82-% E4%B8%AD%E5%9C%8B-%E6%AD%A6%E6%BC%A2%E8%82%BA%E7%82%8E-%E5%B8%82%E6%B0%91% E5%B0%81%E5%9F%8E%E5%89%8D%E9%80%83%E9%9B%A2-%E7%81%AB%E8%BB%8A%E7%AB%99%E5 %87%8C%E6%99%A8%E6%8E%92%E9%95%B7%E9%BE%8D)
According to Wikipedia, the day before the closure of the city, the train sent nearly 300,000 passengers through the three towns of Wuhan. Tianhe International Airport did not close and depart until 13:00 on the 23rd.
Source Wikipedia: Coronavirus Disease 2019 Closure Measures in Mainland China