The State Department on Thursday night raised its China travel advisory to "Level 4: Do Not Travel," citing the spread of the deadly coronavirus, days after evacuating non-emergency U.S. personnel and their families out of the country amid an uptick in infections.

"Those currently in China should consider departing using commercial means. The Department of State has requested that all non-essential U.S. government personnel defer travel to China in light of the novel coronavirus," officials said in the advisory.

It was upgraded from a Level 3 issued earlier this week that urged Americans to reconsider travel to Wuhan, the epicenter of the virus that officials have since quarantined, along with at least 17 other cities.

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The U.S. has been offering additional evacuation flights for private citizens out of China. The State Department said the flights will leave from Wuhan International Airport “on or about Feb. 3" and will be available on a "reimbursable basis."

Roughly 195 Americans were flown out of Wuhan -- the city where the outbreak originated -- earlier this week and are undergoing three days of testing at a Southern California military base before being released.

The World Health Organization on Thursday declared the outbreak a global health emergency after a recent jump in infections, which totaled more than 7,800 as of Thursday. The virus has claimed the lives of at least 170 people.

Over the past 24 hours, there were 38 new deaths and nearly 1,740 reported cases.

Multiple countries have taken extra precautions to stem to the flow of the pneuma-like virus, or 2019-nCoV, from crossing their borders. Six cases have been confirmed in the United States.

Nearly 100 cases have been reported outside of China -- including eight cases of human-to-human transmission in four countries: Germany, Japan, Vietnam and the U.S.

Common symptoms of coronaviruses have resembled those of the common cold. Other strains of the virus such as Severe Acute Respiratory Syndrome (SARS) and Middle East Respiratory Syndrome (MERS) could cause pneumonia and possible death.

The Chinese government has begun construction of hospitals to treat and evaluate patients. Villagers in the suburbs of Beijing have taken measures of their own by sealing off their towns from outsiders.

Their tactics have been similar to ones used during the outbreak of SARS, or severe acute respiratory syndrome, in 2002-03. The disease originated in China and killed nearly 800 people. The current number of coronavirus cases now has surpassed the number of cases of SARS during the outbreak nearly two decades ago, but the current death toll has been lower.

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In China, and several other countries, the sale of surgical masks have skyrocketed as the illness continues to spread beyond China's borders.

Fox News' David Aaro contributed to this report.