Police have long worried that malls are the perfect target for deranged criminals or terrorists.
There is ample evidence that there is good reason for concern -- from a deadly mall shooting in Omaha Wednesday, in which a shooter took nine lives, including his own, to shootings at malls in Georgia and Texas just this past week.
Last February, an 18-year-old fatally shot five people and injured four others during a mall shooting near Salt Lake City in Utah.
In April a mall shooting spree in Kansas City left three dead.
And in 2002, the D.C. snipers murdered at least two people outside of strip malls.
"Malls are always going to be a soft target, but keep in mind they're particularly busy around the holiday season," former FBI agent Brad Garrett told ABC News.
"So for someone to go into a mall and commit the acts this individual has committed, it creates a mindset in the public, are malls really safe to go to?" he continued.
Last month, the FBI and Department of Homeland Security sent out a bulletin warning of a plot to target malls in major cities.
The intelligence was determined to be of weak credibility, but underscores how seriously law enforcement deems the threat.
Now the concern with the holiday season is that the latest tragedy in Omaha will spur copycats.