Plage i Laśkiewicz works, later nationalised as the LWS factory. The Catholic University of Lublin was founded in 1918. In 1921, Roman Catholics constituted 58.9% of the city's population, Jews - 39.5%. In 1931, 63.7% of the inhabitants were Roman Catholic and 34.7% Jewish. On July 20, 1931, a violent tornado carved a path of destruction through the city, destroying dozens of structures in downtown and killing six people. This tornado is officially rated F4 on the Fujita scale; however, the Polish Weather Service estimated winds at , potentially ranking it as an F5. World War II In early September 1939, during the joint German-Soviet invasion of Poland, which started World War II, the Polish government evacuated a portion of the Polish gold reserve from Warsaw to Lublin, and then further east to Łuck, before the city was occupied by Germany, and found itself in the newly formed General Government territory. The Polish population became a target of severe Nazi persecutions focusing on intelligentsia and Polish Jews. In November 1939, during the Intelligenzaktion, the Germans carried out mass arrests of hundreds of Poles, including teachers, judges, lawyers, engineers, lecturers and students of the Catholic University of Lublin, priests, and lecturers of the local theological seminary. The occupiers also closed down the Catholic University of Lublin. Arrested Poles were held in a prison established in the Lublin Castle, and many were afterwards deported to concentration camps. On December 23–25, 1939, the Germans carried out massacres of 31 Poles in several locations in Lublin. Among the victims were lawyers, professors, school principals, starosts of Lublin and Lubartów counties and other well-known and respected citizens of the region. In January and February 1940, the occupiers arrested 23 Capuchin friars and 43 Jesuit friars. Persecution of Polish intelligentsia was continued with the AB-Aktion. On June 24, 1940, the Germans carried out mass arrests of over 800 Poles in Lublin, who were then imprisoned in the castle, along with dozens of Poles who were arrested at the same time in other towns in the region, including Biała Podlaska, Chełm, Puławy. Many of the prisoners were then deported to the Sachsenhausen and Auschwitz concentration camps, while around 500 Poles were murdered in five large massacres carried out in the present-day district of Rury in 1940. Among the victims of the massacres were both men and women: doctors, engineers, local officials, lawyers, judges, activists, military officers, parliamentarians,