This period also saw a significant wave of immigrants from Algeria. As the Algerian War started in 1954, there were already 200,000 Algerian immigrants in France. However, because of the tension between the Algerians and the French, these immigrants were no longer welcome. This conflict between the two sides led to the Paris Massacre of 17 October 1961, when the police used force against an Algerian demonstration on the streets of Paris. After the war, after Algeria gained its independence, the free circulation between France and Algeria was once again allowed, and the number of Algerian immigrants started to increase drastically. From 1962 to 1975, the Algerian immigrant population increased from 350,000 to 700,000. Many of these immigrants were known as the "harkis," and the others were known as the "pieds-noirs." The "harkis" were Algerians who supported the French during the Algerian War; once the war was over, they were deeply resented by other Algerians, and thus had to flee to France. The "pieds-noirs" were Europeans settlers who moved to Algeria, but migrated back to France since 1962 when Algeria declared independence.