Bomb Damages San Diego Courthouse

In what could be the work of a serial bomber, a multi-pipe bomb exploded yesterday at a San Diego courthouse, shattering its door and blasting shrapnel across the street, ABC News reports. No one was hurt in the predawn explosion. The FBI is investigating the incident, which follows a similar bombing in the city last month that destroyed the door of a Federal Express building. No one has claimed responsibility for yesterday's attack, and no threats were received. (More San Diego stories.)