据执法部门消息人士透露，爆炸发生在早上7点30分之前，地点位于东大街的该培训中心内，正是洛杉矶县警长特别执法局和纵火爆破小组的驻地。初步调查显示，爆炸疑似在警员搬动一枚近期在炸弹威胁报警中发现的未爆炸弹药时引发。

LOS ANGELES, July 18 (Xinhua) -- Three detectives were killed Friday morning in an explosion at a police training facility in Southern California, authorities confirmed.