I'm curious as to why the news is stating there is...

I'm curious as to why the news is stating there is only one positive case in Sierra Vista, but at Fort Huachuca they have 4 confirmed cases. Is it my understanding that because it's a military installation it donesn't count as part of Sierra Vista or the??? Why are they still bringing in soldiers from hot spots like California and DC. Delivery drivers are in and out of fort Huachuca constantly raising the risk of spreading.