Also note: I’m talking about 11:40am. These are the pre-SWAT police officers who rushed into the building almost immediately after the shooter entered the building.
SWAT doesn’t arrive until 12:10pm.
So no. For the time-period between 11:40am to 12:10pm, Police are just armed with whatever they got. Normal officers don’t go around with Flash Bangs, Body Armor, AR15s. Most officers just have a handgun until SWAT arrives.