FRESNO, Calif. (AP) — The rustic tent cabins of Yosemite National Park — a favorite among families looking to rough it in one of the nation’s most majestic settings — have become the scene of a public health crisis after two visitors died from a rodent-borne disease following overnight stays.

On Tuesday, park officials sent letters and emails to 1,700 visitors who stayed in some of the dwellings in June, July and August, warning them that they may have been exposed to the disease that also caused two other people to fall ill.

Those four people contracted hantavirus pulmonary syndrome after spending time in one of the 91 “Signature Tent Cabins” at Curry Village around the same time in June. The illness is spread by contact with rodent feces, urine and saliva, or by inhaling exposed airborne particles.

After the first death, the park sanitized the cabins and alerted the public through the media that the cause might have been diseased mice in the park.

However, officials did not know for sure the death was linked to Yosemite or the campsite until the Centers for Disease Control determined over the weekend that a second visitor, a resident of Pennsylvania, also had died.

After every park tragedy, officials stress that Yosemite is a wilderness area and with it come some dangers.

“We’re very concerned about visitors and employees,” park spokesman Scott Gediman said. “But we feel we are taking proactive steps in both cleaning the affected areas and in public education. But it’s absolutely impossible to eliminate all risk.”