A second person has died from a rare virus after camping at Yosemite National Park, according to park officials.

The camper, whose name and gender have yet to be released, died from hantavirus pulmonary syndrome, a flu-like disease spread to humans by exposure to rodent droppings and urine. He had been camping in the California park’s Curry Village Campground, where at least three other campers are thought to have acquired the virus this summer. Two of the four known cases have been fatal.