The headline makes it sound a little more serious than it is. According to the Denver Post a man came into the store and approached the pharmacy. He pulled a firearm from a duffel bag and fired it into the ceiling.
Shoppers in the store heard the noise but didn't associate it with a gun shot. The man is still at large and a simple discussion is included in the news report.
Personal security 101 would suggest that big crowds bring bigger risks to your safety. If you want to increase your family's security this holiday season try shopping during off times. When you do show take the proper precautions. Consider carrying your weapon within the legal limits an in accordance with your own preparation.