A suspected pipe bomb exploded at the federal courthouse in downtown San Diego early Sunday, damaging a door and blowing out a window, authorities said. The loud blast occurred at about 1:40 a.m. at the Edward J. Schwartz Federal Courthouse, said FBI spokeswoman April Langwell. The device caused damage to the front entrance and lobby area of the courthouse, she said.

The bomb was reported by two guards inside the building, who were uninjured. About 40 agents combed the courtyard in front of the courthouse after the area was swept for explosives.