By Keith Coffman
DENVER (Reuters) - A gunshot was fired into President Barack Obama's downtown Denver re-election headquarters on Friday while campaign workers were inside but no one was struck, police said.
Denver Police Detective Raquel Lopez said a worker inside the office called police in mid-afternoon to report that a bullet had shattered a window pane.
"Right now, no one is in custody and investigators are looking at surveillance video to see if a vehicle can be identified," Lopez said.
Lopez said it was a single shot and no one inside was physically injured.
Detectives are not aware of any threats made to the campaign, but are exploring all possibilities, she said.
(Editing by Mary Slosson and Eric Walsh)