AFP: A shot has been fired at a campaign office for President Barack Obama in the western US state of Colorado, shattering a window but injuring no one, police said.        

Staff were in the office when the incident occurred mid-afternoon, yesterday. "It looks like it was one shot that was fired into the structure," said Denver police spokeswoman Raquel Lopez, cited by The Denver Post.        

A photo posted online by the Denver Westword showed a window broken at the front of the office. Police were searching for a "possible vehicle of interest," said Lopez, giving no further details.