Chinese authorities have placed Wuhan, a city of 11 million people, under strict quarantine to stop the spread of the deadly Wuhan coronavirus.
The Wuhan coronavirus is named after the city where the first fatal case was reported. The Wuhan virus is now categorized as an epidemic after the death toll quadrupled overnight.
The virus that causes a deadly type of pneumonia has spread around the world from ground zero in Wuhan city. The CDC confirmed America's first case of Wuhan coronavirus in Washington state.
America, Asia and Europe authorities have canceled planes and trains and screened travelers for the virus. The World Health Organization (WHO) is considering declaring an international emergency.
Chinese authorities shut down public transportation in Wuhan and urged people not to travel to or from Wuhan. The emergency measures were set to take effect at 10 a.m. local time.
Officials said quarantining the city was necessary to "effectively cut off the transmission of the virus, resolutely curb the spread of the epidemic, and ensure the safety and health of the people."
Officials used television, radio and Twitter.com to spread the word that Wuhan and its population were under quarantine. The hashtag #WuhanLockdown was the top trending topic on Twitter.
Sales of surgical masks have skyrocketed in Asian countries.
Citizens of Wuhan took to Twitter to express concern about what would happen to them if they are under quarantine and unable to leave the city.
"Who will think of the lives of those of us who are healthy in Wuhan? We are also afraid," wrote one Twitter user.
"Even before the city was closed, we protected ourselves and hid at home. Now we are lambs who will still be slaughtered, and we can only leave our fates to the heavens."
Others wondered how sick residents would get from their homes to hospitals without public transportation.
Coronaviruses were first identified in the 1960s from nasal swabs of people who had the common cold.
But the new coronavirus leaped from fish and animals to humans. The virus is easily spread via air, replicates rapidly in the lungs and overwhelms the respiratory system.
One critical patient was placed on a heart and lung machine to bypass their lungs until they recovered from the disease.