The security of Paris is mainly the responsibility of the Prefecture of Police of Paris, a subdivision of the Ministry of the Interior of France. It supervises the units of the National Police who patrol the city and the three neighbouring departments. It is also responsible for providing emergency services, including the Paris Fire Brigade. Its headquarters is on Place Louis Lépine on the Île de la Cité. There are 30,200 officers under the prefecture, and a fleet of more than 6,000 vehicles, including police cars, motorcycles, fire trucks, boats and helicopters. In addition to traditional police duties, the local police monitors the number of discount sales held by large stores (no more than two a year are allowed) and verify that, during summer holidays, at least one bakery is open in every neighbourhood. The national police has its own special unit for riot control and crowd control and security of public buildings, called the Compagnies Républicaines de Sécurité (CRS), a unit formed in 1944 right after the liberation of France. Vans of CRS agents are frequently seen in the centre of the city when there are demonstrations and public events.