Were the officers who waited outside for backup armed with military style weapons?
If not, I don’t blame them. The odds would be totally stacked against them. They also would not have known how many shooters there were, causing hesitation.
Until you’re confrtonted with such a situation, it’s pretty stupid to judge them so harshly. I think most reasonable people would have waited for backup. It’s not a movie where the first shot from a pistol always killed the bad guy with a machine gun.