Good one, Hook686. I knew I was forgetting to post something... Yes the whole crossfire situation would be bad, but disciplined shooting would help overcome that. Take as careful a shot as you can, then make it absolutely clear that you are a friendly. That's really all you can do.
It's called situational awareness, and is the 3rd rule of gun handling (always be sure of your target). However, the bad guys don't always wear black hats, and the good guys don't always wear white hats. The tactical training you may be familiar with where you hold on red and shoot on white doesn't apply. Most surprise attacks achieve exactly that, and your situational awareness in that scenario will be somewhere around your ankles. Police are trained to coordinate their response, to confront the suspect with as many guns as possible pointed his way, but to fire only when the suspect makes a hostile action. A random sprinkling of CCWers will likely never have met each other and will have minimal coordination, will be in different places when the situation breaks out, and will likely fire without hesitation when presented with somebody else that has a gun out and is pulling the trigger.
In addition, when the police get there they won't know what the hell is going on; they'll have had dozens of stories about five guys with guns drawn and assume multiple gunmen. Hell, they made that mistake when Hawkins was the only armed man in the mall. You really do not want a SWAT team running in to see you holding a gun, especially if your knee-jerk reaction is to turn and face them.
Despite all that, I would rather have had 3 CCWers not knowing what was going on but prepared to defend themselves in seconds over 50 cops showing up 10 minutes after the first shot and taking another 15 to storm in.
A CHL holder would be useful even if he's not carrying at the time; he'll be more alert than those around him, and will be quicker to gather his wits. You can call non-carriers sheep, but that's a blessing in disguise; shouted orders are much more likely to be followed by scared people, so a CHL who takes in the situation will be able to get people to safety. In a mall, that's really easy; everyone gets into the stores (which give better cover than anything in the concourse as well as an escape route), have the managers close the gates (if they haven't skeddaddled already), and everybody gets out through the back door and the fire corridors.