The New York Police Department's "wall of heroes" has added the names of eight police officers who died of lung diseases after working at ground zero on Sept. 11, 2001 and in the days and weeks that followed. The eight officers and detectives died of diseases they developed after working in the ruins of the World Trade Center cleaning the area of toxic debris. Their names were set onto bronze plaques at a ceremony at police headquarters on Wednesday. Mayor Michael Bloomberg says all officers whose names were added to the wall "put themselves in harm's way to protect us." He says that "future generations will know of their courage and sacrifice."