The U.S. government was racing Monday to evacuate Americans from the city at the center of the deadly coronavirus outbreak in China. As China sends medical reinforcements into Wuhan, officials there warned the virus was spreading faster.

At least 81 people have died in China from the new virus, officially dubbed “2019 novel coronavirus” (2019-nCoV). More than 2,700 others have been infected in more than a dozen countries, including five confirmed cases in the United States. More than 60 additional people in the U.S. were being tested for the disease.

Public health officials from the U.S. and China have warned people to expect many more infections, and there have been unconfirmed claims from anonymous health workers in China that many thousands more than their government is acknowledging could already be infected.

As CBS News correspondent Ramy Inocencio reports, the rapidly mounting cases were making everyone in China nervous, with Wuhan and at least 16 other cities still locked down Monday in a bid to stem the spread of the virus. A combined population of more than 50 million people were under travel restrictions in China as of Monday.

Authorities believe the virus, which causes flu-like symptoms, likely spread into the human population from an infected animal at a market in Wuhan. Officials have confirmed that the virus has been transmitted person-to-person, but it remains unclear how easy it is to contract from another infected individual, and most virtually all cases thus far can be traced back to Wuhan.