A chartered 747 jumbo jet landed at Marine Corp Air Station Miramar on Tuesday carrying 187 Americans evacuated from China under fear of exposure to the Coronavirus.

The evacuees will be held for at least 14 days during the highly contagious virus’ full incubation period. US Center for Disease Control (CDC) staff examined the individuals and determined that four of them needed additional treatment; two adults were taken to UCSD Medical Center, and one adult and one child were transferred to Rady’s Childrens’ Hospital.

“We continue to believe the immediate risk of coronavirus exposure to the general public is low, however, CDC is undertaking these measures to help keep that risk low,” the agency said in a statement released the day after the flight arrived from China.

The flight to Miramar was one of several that have taken Americans evacuated from the Wuhan area of China to US military based chosen as quarantine sites. Miramar, along with March Air Base in Riverside, Travis Air Base in Northern California, Lackland Air Base in Texas, the 168th Regiment Regional Training Institute in Colorado, and Camp Ashland, a National Guard base in Nebraska, were chosen because they can each hold up to 250 people without affecting military operations at those bases.

While at the bases, the individuals will be monitored for symptoms of the virus by CDC staff, and will be provided food and supplies by the US Health and Human Services Department. No military personnel will be used to handle the individuals under the quarantines.

The coronavirus has already claimed at least 490 lives, while more than 24,000 people have been infected in China. The respiratory illness, much like the more common flu, is treatable, but is especially dangerous for the sick, elderly, and young children.

There have been 12 confirmed cases of coronavirus in the United States.