DENVER (AP) -- Denver police are reviewing video footage from city surveillance cameras after a shot was fired through the window of President Barack Obama's campaign office.

Police spokeswoman Raquel Lopez says cameras are in the area of the campaign office on West Ninth Avenue near Acoma Street near Denver's downtown, and investigators are poring over the tapes for any leads. She did not release any other information, citing an "active, ongoing investigation."

Lopez says people were inside the office when the shooting happened Friday afternoon, but no one was injured. A large panel of glass was left shattered at the office.

Lopez says she isn't aware of any previous threats against the campaign office.

The Secret Service referred questions about the shooting to Denver police, and an Obama campaign spokeswoman declined to comment.