Philadelphia continued to grow with immigrants coming from Eastern Europe and Italy, as well as African American migrants from the South. Foreign immigration was briefly interrupted by World War I. The demand for labor for the city's factories, including the new U.S. Naval Yard at Hog Island, which constructed ships, trains, and other items needed in the war effort, helped attract blacks in the Great Migration. In September 1918, cases of the influenza pandemic were reported at the Naval Yard and began to spread. The disease became widespread following the Philadelphia Liberty Loans Parade, which was attended by more than 200,000 people. Mortality on some days was several hundred people and, by the time the pandemic began to subside in October, more than 12,000 people had died.