A suspected pipe bomb exploded at the federal courthouse in downtown San Diego early Sunday, damaging a door and blowing out a window. No one was injured.
Streets in the area were closed until Sunday afternoon. The courthouse will be closed Monday for repairs.
Debris was found lodged in a window about eight stories up a building that faces the courthouse.
Authorities say no threats were received before the explosion and no one has claimed responsibility. Evidence is being sent to an FBI laboratory in Virginia for analysis.