U.S. Forces in Korea (USFK) said Saturday it has imposed a shelter-in-place order on two of its largest bases — U.S. Army Garrison Yongsan and Camp Humphreys — until Tuesday after a cluster of coronavirus infections.

Camp Humphreys in Pyeongtaek, south of Seoul, is the largest U.S. military base overseas, housing the USFK headquarters and thousands of troops, civilian workers, and their family members.

It was not immediately clear how many cases have been reported at the two bases, but USFK said six people tested positive on Friday. The command has been relatively successful in keeping infections down to a handful.