A bomb squad safely detonated a large World War II aerial bomb that was uncovered in the garden of a house in downtown Salzburg, officials said Saturday. The 250-kilogram (550-pound) device set off a huge boom that could be heard across the city when it was exploded as a precaution around 10 p.m. (0800 GMT) Friday, authorities said. Police had evacuated people from homes within a 200-meter (yard) radius of the site and had closed the neighborhood to traffic. Experts were examining the house to determine if the force of the blast caused any damage, officials said. Dieter Vierbach, the head of a private company that assisted in the detonation, said the operation originally was to be carried out on Nov. 12, but that local officials agreed to set off the bomb earlier to eliminate the chances of it going off accidentally.