Two American citizens working for the US Forces Korea tested positive for the coronavirus Friday, USFK said, bringing the total number of infections among its population to 17.

One of the contractors works at Osan Air Base and the other at Camp Humphreys, both located in Pyeongtaek, 70 kilometers south of Seoul, USFK said, adding that they are currently in isolation at their respective off-base residences.

The first patient last visited the base on Wednesday, and authorities have conducted contact tracing as well as disinfection work. He is the first confirmed case from the air base.

The second contractor last visited the garrison last Friday and has not been in contact with any other USFK or USFK-affiliated individuals as he has been in self-quarantine since earlier this week after dining together with another American citizen confirmed to have the virus, USFK added.

The latest cases marked the third straight day the virus was reported in Pyeongtaek. The two previous ones had been confirmed from Camp Humphreys.

Part of the Osan base was shut down accordingly on Friday, as the military brought its Health Protection Condition Levels (HPCON) a notch higher to "Charlie Plus" or "C+" for the Osan base, according to its Facebook post.

The same guidance has been in place for the Pyeongtaek garrison since last week. Several facilities were shuttered, and all movement except for mission essentials and basic needs has been restricted. All other installations are operating at HPCON-Charlie.

Across the peninsula, the military remains at a level of "high" risk, and USFK Commander Gen. Robert Abrams declared a public health emergency to issue related guidance and enforce compliance. (Yonhap)