A British police officer reads messages today placed on flowers in memory of the attack in central London's Tavistock Square a year ago, when a bomb destroyed the No. 30 bus. Three suicide bombers also struck London's Underground system. In all, 52 commuters were killed in the worst attack on London since World War II. A national, two-minute moment of silence was held at noon. The names of the dead will be read during an evening service at Regent's Park.