No one had expected the army to enter the city, so only a few large barricades were already in place, on the Rue Saint-Florentin and Rue de l'Opéra, and the Rue de Rivoli. Barricades had not been prepared in advance; some nine hundred barricades were built hurriedly out of paving stones and sacks of earth. Many other people prepared shelters in the cellars. The first serious fighting took place on the afternoon of the 22nd, an artillery duel between regular army batteries on the Quai d'Orsay and the Madeleine, and National Guard batteries on the terrace of the Tuileries Palace. On the same day, the first executions of National Guard soldiers by the regular army inside Paris took place; some sixteen prisoners captured on the Rue du Bac were given a summary hearing, and then shot.