Late on 18 March, when they learned that the regular army was leaving Paris, units of the National Guard moved quickly to take control of the city. The first to take action were the followers of Blanqui, who went quickly to the Latin Quarter and took charge of the gunpowder stored in the Pantheon, and to the Orleans railway station. Four battalions crossed the Seine and captured the prefecture of police, while other units occupied the former headquarters of the National Guard at the Place Vendôme, as well as the Ministry of Justice. That night, the National Guard occupied the offices vacated by the government; they quickly took over the Ministries of Finance, the Interior, and War. At eight in the morning the next day, the Central Committee was meeting in the Hôtel de Ville. By the end of the day, 20,000 national guardsmen camped in triumph in the square in front of the Hôtel de Ville, with several dozen cannons. A red flag was hoisted over the building.