Fighting a fire at Denver's Southwest Plaza Mall, about two miles from Columbine High, firefighters discovered two tanks of propane and a homemade pipe bomb stored in the food court. Nothing had detonated and no one was injured, yet the implications are downright chilling.

The discovery came on the 12th anniversary of the massacre at the nearby high school. If you recall, shooters Eric Harris and Dylan Klebold had used similar devices during their killing spree. Authorities suspect more than coincidence is at play.

Meanwhile, a "person of interest" has been identified in security footage, described "as a white male with graying hair and a silver mustache."

Photos taken from surveillance show the man in a dark cap, gray and white striped shirt, dark jacket, blue jeans and dark shoes. He is seen entering a stairwell and carrying a white plastic bag.

The mall was evacuated following the discovery, and schools in the area tightened security. Classes at Columbine itself had been cancelled to commemorate the shootings. [AP, photo via AP]