A hydrogen cyanide leak led to a shelter-in-place order affecting thousands of residents in the southern outskirts of Santa Rosa late Wednesday afternoon, Jan. 28. Authorities shut down a portion of Santa Rosa Avenue in connection with the leak, which was reported shortly before 3 p.m. Wednesday. Crews from the Sonoma County Fire District worked to mitigate the hazard, and officials to issue a shelter-in-place order for about two hours. The road closure covered about a half-mile on Santa Rosa Avenue between Todd Road and Mountain View Avenue, Hancock said. Exposure to hydrogen cyanide can interfere with the normal use of oxygen by nearly every organ of the body.