Police dogs have identified the “potential presence of human remains” inside Centennial Mills, according to Portland fire officials. Constructed in 1911, the Centennial Mills building was once integral to the global trade of wheat, Oregon’s chief export for a time in the early 20th century. Amtrak typically runs around 16 passenger trains per day on the corridor past Centennial Mills, including the Portland to Spokane and Chicago. On the freight side, with a switching terminal located just north of Centennial Mills now inaccessible, the two railroads that use the corridor—Union Pacific Railroad and BNSF Railway—have been diverting railcars outside Portland. City officials say they’re working with federal, state and county authorities to monitor air quality and debris.