Additional improvements and routine maintenance work were completed in the early 1910s. A greenhouse was built in 1910, and the contagious-diseases ward on island 3 opened the following June. In addition, the incinerator was replaced in 1911, and a recreation center operated by the American Red Cross was also built on island 2 by 1915. These facilities generally followed the design set by Tilton and Boring. When the Black Tom explosion occurred on Black Tom Island in 1916, the complex suffered moderate damage; though all immigrants were evacuated safely, the main building's roof collapsed, and windows were broken. The main building's roof was replaced with a Guastavino-tiled arched ceiling by 1918. The immigration station was temporarily closed during World War I in 1917–1919, during which the facilities were used as a jail for suspected enemy combatants, and later as a treatment center for wounded American soldiers. Immigration inspections were conducted aboard ships or at docks. During the war, immigration processing at Ellis Island declined by 97%, from 878,000 immigrants per year in 1914 to 26,000 per year in 1919.