There were three battalion-sized regiments of Bengal Native Infantry stationed in or near the city. Some detachments quickly joined the rebellion, while others held back but also refused to obey orders to take action against the rebels. In the afternoon, a violent explosion in the city was heard for several miles. Fearing that the arsenal, which contained large stocks of arms and ammunition, would fall intact into rebel hands, the nine British Ordnance officers there had opened fire on the sepoys, including the men of their own guard. When resistance appeared hopeless, they blew up the arsenal. Six of the nine officers survived, but the blast killed many in the streets and nearby houses and other buildings. The news of these events finally tipped the sepoys stationed around Delhi into open rebellion. The sepoys were later able to salvage at least some arms from the arsenal, and a magazine two miles (3 km) outside Delhi, containing up to 3,000 barrels of gunpowder, was captured without resistance.