BOZEMAN, Mont. (AP) — Health officials are warning that the there is evidence that the coronavirus has been spreading within southwestern Montana's Gallatin County. They are stressing the need for the public to take precautions to prevent more people from being exposed to it. Unlike the county's first four cases of the coronavirus, the four people confirmed to have COVID-19 on Saturday have no known source of infection. The Gallatin-City County Health Department says they had no known travel history, exposure to someone who traveled or exposure to other known COVID-19 cases. The department says all four have had mild symptoms and have been isolated. Those who had close contacts with them have been quarantined.